Move Diskstream ownership to Track, so that Session no longer holds lists of Diskstre...
[ardour.git] / gtk2_ardour / editor_ops.cc
index 159336bf67c76f6ebe5f8d0db390176df2e431e8..7f3aa7f7a84347feef185d86eb0fb86b05e562c7 100644 (file)
 #include "pbd/pthread_utils.h"
 #include "pbd/memento_command.h"
 #include "pbd/whitespace.h"
+#include "pbd/stateful_diff_command.h"
 
 #include <gtkmm2ext/utils.h>
 #include <gtkmm2ext/choice.h>
-#include <gtkmm2ext/window_title.h>
 #include <gtkmm2ext/popup.h>
 
 #include "ardour/audioengine.h"
@@ -45,7 +45,6 @@
 #include "ardour/audio_diskstream.h"
 #include "ardour/utils.h"
 #include "ardour/location.h"
-#include "ardour/named_selection.h"
 #include "ardour/audio_track.h"
 #include "ardour/audioplaylist.h"
 #include "ardour/region_factory.h"
 #include "editor_routes.h"
 #include "editor_regions.h"
 #include "quantize_dialog.h"
+#include "interthread_progress_window.h"
 
 #include "i18n.h"
 
 using namespace std;
 using namespace ARDOUR;
 using namespace PBD;
-using namespace sigc;
 using namespace Gtk;
 using namespace Gtkmm2ext;
 using namespace Editing;
+using Gtkmm2ext::Keyboard;
 
 /***********************************************************************
   Editor operations
@@ -98,16 +98,16 @@ using namespace Editing;
 void
 Editor::undo (uint32_t n)
 {
-       if (session) {
-               session->undo (n);
+       if (_session) {
+               _session->undo (n);
        }
 }
 
 void
 Editor::redo (uint32_t n)
 {
-       if (session) {
-               session->redo (n);
+       if (_session) {
+               _session->redo (n);
        }
 }
 
@@ -126,7 +126,7 @@ Editor::split_regions_at (nframes64_t where, RegionSelection& regions)
        // region boundaries, don't pay attention to them
 
        if (regions.size() == 1) {
-               switch (snap_type) {
+               switch (_snap_type) {
                case SnapToRegionStart:
                case SnapToRegionSync:
                case SnapToRegionEnd:
@@ -156,7 +156,13 @@ Editor::split_regions_at (nframes64_t where, RegionSelection& regions)
 
                boost::shared_ptr<Playlist> pl = (*a)->region()->playlist();
 
-               if (! pl->frozen()) {
+                if (!pl) {
+                        cerr << "region " << (*a)->region()->name() << " has no playlist!\n";
+                        a = tmp;
+                        continue;
+                }
+
+               if (!pl->frozen()) {
                        /* we haven't seen this playlist before */
 
                        /* remember used playlists so we can thaw them later */
@@ -170,10 +176,9 @@ Editor::split_regions_at (nframes64_t where, RegionSelection& regions)
                }
 
                if (pl) {
-                       XMLNode &before = pl->get_state();
+                        pl->clear_history ();
                        pl->split_region ((*a)->region(), where);
-                       XMLNode &after = pl->get_state();
-                       session->add_command(new MementoCommand<Playlist>(*pl, &before, &after));
+                       _session->add_command (new StatefulDiffCommand (pl));
                }
 
                a = tmp;
@@ -249,14 +254,8 @@ Editor::extend_selection_to_end_of_region (bool next)
                start = selection->time.start ();
        }
 
-       /* Try to leave the selection with the same route if possible */
-
-       if ((tv = selection->time.track) == 0) {
-               return;
-       }
-
        begin_reversible_command (_("extend selection"));
-       selection->set (tv, start, region->position() + region->length());
+       selection->set (start, region->position() + region->length());
        commit_reversible_command ();
 }
 
@@ -279,12 +278,8 @@ Editor::extend_selection_to_start_of_region (bool previous)
 
        /* Try to leave the selection with the same route if possible */
 
-       if ((tv = selection->time.track) == 0) {
-               return;
-       }
-
        begin_reversible_command (_("extend selection"));
-       selection->set (tv, region->position(), end);
+       selection->set (region->position(), end);
        commit_reversible_command ();
 }
 
@@ -320,7 +315,7 @@ Editor::nudge_forward (bool next, bool force_playhead)
 
        get_regions_for_action (rs);
 
-       if (!session) return;
+       if (!_session) return;
 
        if (!force_playhead && !rs.empty()) {
 
@@ -335,10 +330,9 @@ Editor::nudge_forward (bool next, bool force_playhead)
                                distance = next_distance;
                        }
 
-                        XMLNode &before = r->playlist()->get_state();
+                        r->clear_history ();
                        r->set_position (r->position() + distance, this);
-                        XMLNode &after = r->playlist()->get_state();
-                       session->add_command (new MementoCommand<Playlist>(*(r->playlist()), &before, &after));
+                       _session->add_command (new StatefulDiffCommand (r));
                }
 
                commit_reversible_command ();
@@ -380,7 +374,7 @@ Editor::nudge_forward (bool next, bool force_playhead)
                                        }
                                }
                                XMLNode& after (loc->get_state());
-                               session->add_command (new MementoCommand<Location>(*loc, &before, &after));
+                               _session->add_command (new MementoCommand<Location>(*loc, &before, &after));
                        }
                }
 
@@ -388,7 +382,7 @@ Editor::nudge_forward (bool next, bool force_playhead)
 
        } else {
                distance = get_nudge_distance (playhead_cursor->current_frame, next_distance);
-               session->request_locate (playhead_cursor->current_frame + distance);
+               _session->request_locate (playhead_cursor->current_frame + distance);
        }
 }
 
@@ -401,7 +395,7 @@ Editor::nudge_backward (bool next, bool force_playhead)
 
        get_regions_for_action (rs);
 
-       if (!session) return;
+       if (!_session) return;
 
        if (!force_playhead && !rs.empty()) {
 
@@ -415,16 +409,15 @@ Editor::nudge_backward (bool next, bool force_playhead)
                        if (next) {
                                distance = next_distance;
                        }
-
-                        XMLNode &before = r->playlist()->get_state();
+                        
+                        r->clear_history ();
 
                        if (r->position() > distance) {
                                r->set_position (r->position() - distance, this);
                        } else {
                                r->set_position (0, this);
                        }
-                        XMLNode &after = r->playlist()->get_state();
-                       session->add_command(new MementoCommand<Playlist>(*(r->playlist()), &before, &after));
+                       _session->add_command (new StatefulDiffCommand (r));
                }
 
                commit_reversible_command ();
@@ -468,7 +461,7 @@ Editor::nudge_backward (bool next, bool force_playhead)
                                }
 
                                XMLNode& after (loc->get_state());
-                               session->add_command (new MementoCommand<Location>(*loc, &before, &after));
+                               _session->add_command (new MementoCommand<Location>(*loc, &before, &after));
                        }
                }
 
@@ -479,9 +472,9 @@ Editor::nudge_backward (bool next, bool force_playhead)
                distance = get_nudge_distance (playhead_cursor->current_frame, next_distance);
 
                if (playhead_cursor->current_frame > distance) {
-                       session->request_locate (playhead_cursor->current_frame - distance);
+                       _session->request_locate (playhead_cursor->current_frame - distance);
                } else {
-                       session->goto_start();
+                       _session->goto_start();
                }
        }
 }
@@ -494,21 +487,20 @@ Editor::nudge_forward_capture_offset ()
 
        get_regions_for_action (rs);
 
-       if (!session) return;
+       if (!_session) return;
 
        if (!rs.empty()) {
 
                begin_reversible_command (_("nudge forward"));
 
-               distance = session->worst_output_latency();
+               distance = _session->worst_output_latency();
 
                for (RegionSelection::iterator i = rs.begin(); i != rs.end(); ++i) {
                        boost::shared_ptr<Region> r ((*i)->region());
 
-                       XMLNode &before = r->playlist()->get_state();
+                        r->clear_history ();
                        r->set_position (r->position() + distance, this);
-                       XMLNode &after = r->playlist()->get_state();
-                       session->add_command(new MementoCommand<Playlist>(*(r->playlist()), &before, &after));
+                       _session->add_command(new StatefulDiffCommand (r));
                }
 
                commit_reversible_command ();
@@ -524,26 +516,25 @@ Editor::nudge_backward_capture_offset ()
 
        get_regions_for_action (rs);
 
-       if (!session) return;
+       if (!_session) return;
 
        if (!rs.empty()) {
 
                begin_reversible_command (_("nudge forward"));
 
-               distance = session->worst_output_latency();
+               distance = _session->worst_output_latency();
 
                for (RegionSelection::iterator i = rs.begin(); i != rs.end(); ++i) {
                        boost::shared_ptr<Region> r ((*i)->region());
 
-                        XMLNode &before = r->playlist()->get_state();
+                        r->clear_history ();
 
                        if (r->position() > distance) {
                                r->set_position (r->position() - distance, this);
                        } else {
                                r->set_position (0, this);
                        }
-                        XMLNode &after = r->playlist()->get_state();
-                       session->add_command(new MementoCommand<Playlist>(*(r->playlist()), &before, &after));
+                       _session->add_command(new StatefulDiffCommand (r));
                }
 
                commit_reversible_command ();
@@ -555,14 +546,14 @@ Editor::nudge_backward_capture_offset ()
 void
 Editor::move_to_start ()
 {
-       session->goto_start ();
+       _session->goto_start ();
 }
 
 void
 Editor::move_to_end ()
 {
 
-       session->request_locate (session->current_end_frame());
+       _session->request_locate (_session->current_end_frame());
 }
 
 void
@@ -576,11 +567,11 @@ Editor::build_region_boundary_cache ()
 
        region_boundary_cache.clear ();
 
-       if (session == 0) {
+       if (_session == 0) {
                return;
        }
 
-       switch (snap_type) {
+       switch (_snap_type) {
        case SnapToRegionStart:
                interesting_points.push_back (Start);
                break;
@@ -595,7 +586,7 @@ Editor::build_region_boundary_cache ()
                interesting_points.push_back (End);
                break;
        default:
-               fatal << string_compose (_("build_region_boundary_cache called with snap_type = %1"), snap_type) << endmsg;
+               fatal << string_compose (_("build_region_boundary_cache called with snap_type = %1"), _snap_type) << endmsg;
                /*NOTREACHED*/
                return;
        }
@@ -609,7 +600,7 @@ Editor::build_region_boundary_cache ()
                tlist = track_views;
        }
 
-       while (pos < session->current_end_frame() && !at_end) {
+       while (pos < _session->current_end_frame() && !at_end) {
 
                nframes64_t rpos;
                nframes64_t lpos = max_frames;
@@ -646,8 +637,8 @@ Editor::build_region_boundary_cache ()
                        RouteTimeAxisView *rtav;
 
                        if (ontrack != 0 && (rtav = dynamic_cast<RouteTimeAxisView*>(ontrack)) != 0 ) {
-                               if (rtav->get_diskstream() != 0) {
-                                       speed = rtav->get_diskstream()->speed();
+                               if (rtav->track() != 0) {
+                                       speed = rtav->track()->speed();
                                }
                        }
 
@@ -701,8 +692,8 @@ Editor::find_next_region (nframes64_t frame, RegionPoint point, int32_t dir, Tra
 
                track_speed = 1.0f;
                if ( (rtav = dynamic_cast<RouteTimeAxisView*>(*i)) != 0 ) {
-                       if (rtav->get_diskstream()!=0)
-                               track_speed = rtav->get_diskstream()->speed();
+                       if (rtav->track()!=0)
+                               track_speed = rtav->track()->speed();
                }
 
                track_frame = session_frame_to_track_frame(frame, track_speed);
@@ -726,7 +717,7 @@ Editor::find_next_region (nframes64_t frame, RegionPoint point, int32_t dir, Tra
                        break;
                }
 
-               // rpos is a "track frame", converting it to "session frame"
+               // rpos is a "track frame", converting it to "_session frame"
                rpos = track_frame_to_session_frame(rpos, track_speed);
 
                if (rpos > frame) {
@@ -819,7 +810,7 @@ Editor::cursor_to_region_boundary (bool with_selection, int32_t dir)
        nframes64_t pos = playhead_cursor->current_frame;
        nframes64_t target;
 
-       if (!session) {
+       if (!_session) {
                return;
        }
 
@@ -832,8 +823,7 @@ Editor::cursor_to_region_boundary (bool with_selection, int32_t dir)
                return;
        }
 
-
-       session->request_locate (target);
+       _session->request_locate (target);
 }
 
 void
@@ -854,7 +844,7 @@ Editor::cursor_to_region_point (EditorCursor* cursor, RegionPoint point, int32_t
        boost::shared_ptr<Region> r;
        nframes64_t pos = cursor->current_frame;
 
-       if (!session) {
+       if (!_session) {
                return;
        }
 
@@ -903,15 +893,15 @@ Editor::cursor_to_region_point (EditorCursor* cursor, RegionPoint point, int32_t
        RouteTimeAxisView *rtav;
 
        if ( ontrack != 0 && (rtav = dynamic_cast<RouteTimeAxisView*>(ontrack)) != 0 ) {
-               if (rtav->get_diskstream() != 0) {
-                       speed = rtav->get_diskstream()->speed();
+               if (rtav->track() != 0) {
+                       speed = rtav->track()->speed();
                }
        }
 
        pos = track_frame_to_session_frame(pos, speed);
 
        if (cursor == playhead_cursor) {
-               session->request_locate (pos);
+               _session->request_locate (pos);
        } else {
                cursor->set_position (pos);
        }
@@ -955,7 +945,7 @@ Editor::cursor_to_selection_start (EditorCursor *cursor)
        }
 
        if (cursor == playhead_cursor) {
-               session->request_locate (pos);
+               _session->request_locate (pos);
        } else {
                cursor->set_position (pos);
        }
@@ -987,7 +977,7 @@ Editor::cursor_to_selection_end (EditorCursor *cursor)
        }
 
        if (cursor == playhead_cursor) {
-               session->request_locate (pos);
+               _session->request_locate (pos);
        } else {
                cursor->set_position (pos);
        }
@@ -1000,7 +990,7 @@ Editor::selected_marker_to_region_boundary (bool with_selection, int32_t dir)
        Location* loc;
        bool ignored;
 
-       if (!session) {
+       if (!_session) {
                return;
        }
 
@@ -1053,7 +1043,7 @@ Editor::selected_marker_to_region_point (RegionPoint point, int32_t dir)
        Location* loc;
        bool ignored;
 
-       if (!session || selection->markers.empty()) {
+       if (!_session || selection->markers.empty()) {
                return;
        }
 
@@ -1100,8 +1090,8 @@ Editor::selected_marker_to_region_point (RegionPoint point, int32_t dir)
        RouteTimeAxisView *rtav;
 
        if (ontrack != 0 && (rtav = dynamic_cast<RouteTimeAxisView*>(ontrack)) != 0) {
-               if (rtav->get_diskstream() != 0) {
-                       speed = rtav->get_diskstream()->speed();
+               if (rtav->track() != 0) {
+                       speed = rtav->track()->speed();
                }
        }
 
@@ -1129,7 +1119,7 @@ Editor::selected_marker_to_selection_start ()
        Location* loc;
        bool ignored;
 
-       if (!session || selection->markers.empty()) {
+       if (!_session || selection->markers.empty()) {
                return;
        }
 
@@ -1168,7 +1158,7 @@ Editor::selected_marker_to_selection_end ()
        Location* loc;
        bool ignored;
 
-       if (!session || selection->markers.empty()) {
+       if (!_session || selection->markers.empty()) {
                return;
        }
 
@@ -1230,7 +1220,7 @@ Editor::scroll_playhead (bool forward)
                }
        }
 
-       session->request_locate (pos);
+       _session->request_locate (pos);
 }
 
 void
@@ -1245,7 +1235,7 @@ Editor::playhead_backward ()
                cnt = 1;
        } else {
                if (was_floating) {
-                       cnt = (nframes64_t) floor (prefix * session->frame_rate ());
+                       cnt = (nframes64_t) floor (prefix * _session->frame_rate ());
                } else {
                        cnt = (nframes64_t) prefix;
                }
@@ -1264,7 +1254,7 @@ Editor::playhead_backward ()
           reload, just to move 1 sample !!!
        */
 
-       session->request_locate (pos);
+       _session->request_locate (pos);
 }
 
 void
@@ -1279,7 +1269,7 @@ Editor::playhead_forward ()
                cnt = 1;
        } else {
                if (was_floating) {
-                       cnt = (nframes64_t) floor (prefix * session->frame_rate ());
+                       cnt = (nframes64_t) floor (prefix * _session->frame_rate ());
                } else {
                        cnt = (nframes64_t) floor (prefix);
                }
@@ -1292,13 +1282,13 @@ Editor::playhead_forward ()
           reload, just to move 1 sample !!!
        */
 
-       session->request_locate (pos+cnt);
+       _session->request_locate (pos+cnt);
 }
 
 void
 Editor::cursor_align (bool playhead_to_edit)
 {
-       if (!session) {
+       if (!_session) {
                return;
        }
 
@@ -1308,7 +1298,7 @@ Editor::cursor_align (bool playhead_to_edit)
                        return;
                }
 
-               session->request_locate (selection->markers.front()->position(), session->transport_rolling());
+               _session->request_locate (selection->markers.front()->position(), _session->transport_rolling());
 
        } else {
                /* move selected markers to playhead */
@@ -1340,7 +1330,7 @@ Editor::edit_cursor_backward ()
                cnt = 1;
        } else {
                if (was_floating) {
-                       cnt = (nframes64_t) floor (prefix * session->frame_rate ());
+                       cnt = (nframes64_t) floor (prefix * _session->frame_rate ());
                } else {
                        cnt = (nframes64_t) prefix;
                }
@@ -1371,7 +1361,7 @@ Editor::edit_cursor_forward ()
                cnt = 1;
        } else {
                if (was_floating) {
-                       cnt = (nframes64_t) floor (prefix * session->frame_rate ());
+                       cnt = (nframes64_t) floor (prefix * _session->frame_rate ());
                } else {
                        cnt = (nframes64_t) floor (prefix);
                }
@@ -1393,12 +1383,12 @@ Editor::goto_frame ()
        }
 
        if (was_floating) {
-               frame = (nframes64_t) floor (prefix * session->frame_rate());
+               frame = (nframes64_t) floor (prefix * _session->frame_rate());
        } else {
                frame = (nframes64_t) floor (prefix);
        }
 
-       session->request_locate (frame);
+       _session->request_locate (frame);
 }
 
 void
@@ -1414,7 +1404,7 @@ Editor::scroll_backward (float pages)
                cnt = (nframes64_t) floor (pages * one_page);
        } else {
                if (was_floating) {
-                       cnt = (nframes64_t) floor (prefix * session->frame_rate());
+                       cnt = (nframes64_t) floor (prefix * _session->frame_rate());
                } else {
                        cnt = (nframes64_t) floor (prefix * one_page);
                }
@@ -1442,7 +1432,7 @@ Editor::scroll_forward (float pages)
                cnt = (nframes64_t) floor (pages * one_page);
        } else {
                if (was_floating) {
-                       cnt = (nframes64_t) floor (prefix * session->frame_rate());
+                       cnt = (nframes64_t) floor (prefix * _session->frame_rate());
                } else {
                        cnt = (nframes64_t) floor (prefix * one_page);
                }
@@ -1497,21 +1487,19 @@ Editor::scroll_tracks_up ()
 void
 Editor::scroll_tracks_down_line ()
 {
+       double vert_value = vertical_adjustment.get_value() + 60;
 
-        Gtk::Adjustment* adj = edit_vscrollbar.get_adjustment();
-       double vert_value = adj->get_value() + 60;
-
-       if (vert_value>adj->get_upper() - _canvas_height) {
-               vert_value = adj->get_upper() - _canvas_height;
+       if (vert_value > vertical_adjustment.get_upper() - _canvas_height) {
+               vert_value = vertical_adjustment.get_upper() - _canvas_height;
        }
-       adj->set_value (vert_value);
+       
+       vertical_adjustment.set_value (vert_value);
 }
 
 void
 Editor::scroll_tracks_up_line ()
 {
-        Gtk::Adjustment* adj = edit_vscrollbar.get_adjustment();
-       adj->set_value (adj->get_value() - 60);
+       reset_y_origin (vertical_adjustment.get_value() - 60);
 }
 
 /* ZOOM */
@@ -1519,7 +1507,7 @@ Editor::scroll_tracks_up_line ()
 void
 Editor::tav_zoom_step (bool coarser)
 {
-       ENSURE_GUI_THREAD (bind (mem_fun (*this, &Editor::temporal_zoom_step), coarser));
+       ENSURE_GUI_THREAD (*this, &Editor::temporal_zoom_step, coarser)
 
        _routes->suspend_redisplay ();
 
@@ -1534,7 +1522,7 @@ Editor::tav_zoom_step (bool coarser)
 void
 Editor::temporal_zoom_step (bool coarser)
 {
-       ENSURE_GUI_THREAD (bind (mem_fun (*this, &Editor::temporal_zoom_step), coarser));
+       ENSURE_GUI_THREAD (*this, &Editor::temporal_zoom_step, coarser)
 
        double nfpu;
 
@@ -1552,7 +1540,7 @@ Editor::temporal_zoom_step (bool coarser)
 void
 Editor::temporal_zoom (gdouble fpu)
 {
-       if (!session) return;
+       if (!_session) return;
 
        nframes64_t current_page = current_page_frames();
        nframes64_t current_leftmost = leftmost_frame;
@@ -1568,7 +1556,7 @@ Editor::temporal_zoom (gdouble fpu)
 
        /* XXX this limit is also in ::set_frames_per_unit() */
 
-       if (frames_per_unit <= 2.0 && fpu <= frames_per_unit) {
+       if (frames_per_unit <= 1.0 && fpu <= frames_per_unit) {
                return;
        }
 
@@ -1601,11 +1589,8 @@ Editor::temporal_zoom (gdouble fpu)
                break;
 
        case ZoomFocusPlayhead:
-               /* try to keep the playhead in the same place */
-
-               where = playhead_cursor->current_frame;
-
-               l = - ((new_page_size * ((where - current_leftmost)/(double)current_page)) - where);
+               /* centre playhead */
+               l = playhead_cursor->current_frame - (new_page_size * 0.5);
 
                if (l < 0) {
                        leftmost_after_zoom = 0;
@@ -1668,7 +1653,7 @@ Editor::temporal_zoom (gdouble fpu)
 
        }
 
-       // leftmost_after_zoom = min (leftmost_after_zoom, session->current_end_frame());
+       // leftmost_after_zoom = min (leftmost_after_zoom, _session->current_end_frame());
 
        reposition_and_zoom (leftmost_after_zoom, nfpu);
 }
@@ -1767,18 +1752,13 @@ Editor::temporal_zoom_region (bool both_axes)
                no_save_visual = false;
        }
 
-       zoomed_to_region = true;
        redo_visual_stack.push_back (current_visual_state());
 }
 
 void
-Editor::toggle_zoom_region (bool both_axes)
+Editor::zoom_to_region (bool both_axes)
 {
-       if (zoomed_to_region) {
-               swap_visual_state ();
-       } else {
-               temporal_zoom_region (both_axes);
-       }
+       temporal_zoom_region (both_axes);
 }
 
 void
@@ -1799,17 +1779,17 @@ Editor::temporal_zoom_selection ()
 void
 Editor::temporal_zoom_session ()
 {
-       ENSURE_GUI_THREAD (mem_fun (*this, &Editor::temporal_zoom_session));
+       ENSURE_GUI_THREAD (*this, &Editor::temporal_zoom_session)
 
-       if (session) {
-               temporal_zoom_by_frame (session->current_start_frame(), session->current_end_frame(), "zoom to session");
+       if (_session) {
+               temporal_zoom_by_frame (_session->current_start_frame(), _session->current_end_frame(), "zoom to _session");
        }
 }
 
 void
 Editor::temporal_zoom_by_frame (nframes64_t start, nframes64_t end, const string & /*op*/)
 {
-       if (!session) return;
+       if (!_session) return;
 
        if ((start == 0 && end == 0) || end < start) {
                return;
@@ -1833,7 +1813,7 @@ Editor::temporal_zoom_by_frame (nframes64_t start, nframes64_t end, const string
 void
 Editor::temporal_zoom_to_frame (bool coarser, nframes64_t frame)
 {
-       if (!session) {
+       if (!_session) {
                return;
        }
        double range_before = frame - leftmost_frame;
@@ -1859,8 +1839,8 @@ Editor::temporal_zoom_to_frame (bool coarser, nframes64_t frame)
                new_leftmost = 0;
        }
 //     begin_reversible_command (_("zoom to frame"));
-//     session->add_undo (bind (mem_fun(*this, &Editor::reposition_and_zoom), leftmost_frame, frames_per_unit));
-//     session->add_redo (bind (mem_fun(*this, &Editor::reposition_and_zoom), new_leftmost, new_fpu));
+//     _session->add_undo (sigc::bind (sigc::mem_fun(*this, &Editor::reposition_and_zoom), leftmost_frame, frames_per_unit));
+//     _session->add_redo (sigc::bind (sigc::mem_fun(*this, &Editor::reposition_and_zoom), new_leftmost, new_fpu));
 //     commit_reversible_command ();
 
        reposition_and_zoom (new_leftmost, new_fpu);
@@ -1879,10 +1859,7 @@ Editor::choose_new_marker_name(string &name) {
 
        dialog.set_prompt (_("New Name:"));
 
-       WindowTitle title(Glib::get_application_name());
-       title += _("Name New Location Marker");
-
-       dialog.set_title(title.get_string());
+       dialog.set_title (_("New Location Marker"));
 
        dialog.set_name ("MarkNameWindow");
        dialog.set_size_request (250, -1);
@@ -1915,22 +1892,22 @@ Editor::add_location_from_selection ()
                return;
        }
 
-       if (session == 0 || clicked_axisview == 0) {
+       if (_session == 0 || clicked_axisview == 0) {
                return;
        }
 
        nframes64_t start = selection->time[clicked_selection].start;
        nframes64_t end = selection->time[clicked_selection].end;
 
-       session->locations()->next_available_name(rangename,"selection");
+       _session->locations()->next_available_name(rangename,"selection");
        Location *location = new Location (start, end, rangename, Location::IsRangeMarker);
 
-       session->begin_reversible_command (_("add marker"));
-        XMLNode &before = session->locations()->get_state();
-       session->locations()->add (location, true);
-        XMLNode &after = session->locations()->get_state();
-       session->add_command(new MementoCommand<Locations>(*(session->locations()), &before, &after));
-       session->commit_reversible_command ();
+       _session->begin_reversible_command (_("add marker"));
+        XMLNode &before = _session->locations()->get_state();
+       _session->locations()->add (location, true);
+        XMLNode &after = _session->locations()->get_state();
+       _session->add_command(new MementoCommand<Locations>(*(_session->locations()), &before, &after));
+       _session->commit_reversible_command ();
 }
 
 void
@@ -1940,23 +1917,23 @@ Editor::add_location_mark (nframes64_t where)
 
        select_new_marker = true;
 
-       session->locations()->next_available_name(markername,"mark");
+       _session->locations()->next_available_name(markername,"mark");
        if (!choose_new_marker_name(markername)) {
                return;
        }
        Location *location = new Location (where, where, markername, Location::IsMark);
-       session->begin_reversible_command (_("add marker"));
-        XMLNode &before = session->locations()->get_state();
-       session->locations()->add (location, true);
-        XMLNode &after = session->locations()->get_state();
-       session->add_command(new MementoCommand<Locations>(*(session->locations()), &before, &after));
-       session->commit_reversible_command ();
+       _session->begin_reversible_command (_("add marker"));
+        XMLNode &before = _session->locations()->get_state();
+       _session->locations()->add (location, true);
+        XMLNode &after = _session->locations()->get_state();
+       _session->add_command(new MementoCommand<Locations>(*(_session->locations()), &before, &after));
+       _session->commit_reversible_command ();
 }
 
 void
 Editor::add_location_from_playhead_cursor ()
 {
-       add_location_mark (session->audible_frame());
+       add_location_mark (_session->audible_frame());
 }
 
 void
@@ -1970,8 +1947,8 @@ Editor::add_locations_from_audio_region ()
                return;
        }
 
-       session->begin_reversible_command (rs.size () > 1 ? _("add markers") : _("add marker"));
-       XMLNode &before = session->locations()->get_state();
+       _session->begin_reversible_command (rs.size () > 1 ? _("add markers") : _("add marker"));
+       XMLNode &before = _session->locations()->get_state();
 
        cerr << "Add locations\n";
 
@@ -1981,12 +1958,12 @@ Editor::add_locations_from_audio_region ()
 
                Location *location = new Location (region->position(), region->last_frame(), region->name(), Location::IsRangeMarker);
 
-               session->locations()->add (location, true);
+               _session->locations()->add (location, true);
        }
 
-       XMLNode &after = session->locations()->get_state();
-       session->add_command (new MementoCommand<Locations>(*(session->locations()), &before, &after));
-       session->commit_reversible_command ();
+       XMLNode &after = _session->locations()->get_state();
+       _session->add_command (new MementoCommand<Locations>(*(_session->locations()), &before, &after));
+       _session->commit_reversible_command ();
 }
 
 void
@@ -2000,13 +1977,13 @@ Editor::add_location_from_audio_region ()
                return;
        }
 
-       session->begin_reversible_command (_("add marker"));
-       XMLNode &before = session->locations()->get_state();
+       _session->begin_reversible_command (_("add marker"));
+       XMLNode &before = _session->locations()->get_state();
 
        string markername;
 
        if (rs.size() > 1) {            // more than one region selected
-               session->locations()->next_available_name(markername, "regions");
+               _session->locations()->next_available_name(markername, "regions");
        } else {
                RegionView* rv = *(rs.begin());
                boost::shared_ptr<Region> region = rv->region();
@@ -2021,11 +1998,11 @@ Editor::add_location_from_audio_region ()
 
        // single range spanning all selected
        Location *location = new Location (rs.start(), rs.end_frame(), markername, Location::IsRangeMarker);
-       session->locations()->add (location, true);
+       _session->locations()->add (location, true);
 
-       XMLNode &after = session->locations()->get_state();
-       session->add_command (new MementoCommand<Locations>(*(session->locations()), &before, &after));
-       session->commit_reversible_command ();
+       XMLNode &after = _session->locations()->get_state();
+       _session->add_command (new MementoCommand<Locations>(*(_session->locations()), &before, &after));
+       _session->commit_reversible_command ();
 }
 
 void
@@ -2086,32 +2063,32 @@ Editor::search_forwards ()
 void
 Editor::jump_forward_to_mark ()
 {
-       if (!session) {
+       if (!_session) {
                return;
        }
 
-       Location *location = session->locations()->first_location_after (playhead_cursor->current_frame);
+       Location *location = _session->locations()->first_location_after (playhead_cursor->current_frame);
 
        if (location) {
-               session->request_locate (location->start(), session->transport_rolling());
+               _session->request_locate (location->start(), _session->transport_rolling());
        } else {
-               session->request_locate (session->current_end_frame());
+               _session->request_locate (_session->current_end_frame());
        }
 }
 
 void
 Editor::jump_backward_to_mark ()
 {
-       if (!session) {
+       if (!_session) {
                return;
        }
 
-       Location *location = session->locations()->first_location_before (playhead_cursor->current_frame);
+       Location *location = _session->locations()->first_location_before (playhead_cursor->current_frame);
 
        if (location) {
-               session->request_locate (location->start(), session->transport_rolling());
+               _session->request_locate (location->start(), _session->transport_rolling());
        } else {
-               session->goto_start ();
+               _session->goto_start ();
        }
 }
 
@@ -2124,66 +2101,66 @@ Editor::set_mark ()
        string markername;
 
        if (get_prefix (prefix, was_floating)) {
-               pos = session->audible_frame ();
+               pos = _session->audible_frame ();
        } else {
                if (was_floating) {
-                       pos = (nframes64_t) floor (prefix * session->frame_rate ());
+                       pos = (nframes64_t) floor (prefix * _session->frame_rate ());
                } else {
                        pos = (nframes64_t) floor (prefix);
                }
        }
 
-       session->locations()->next_available_name(markername,"mark");
+       _session->locations()->next_available_name(markername,"mark");
        if (!choose_new_marker_name(markername)) {
                return;
        }
-       session->locations()->add (new Location (pos, 0, markername, Location::IsMark), true);
+       _session->locations()->add (new Location (pos, 0, markername, Location::IsMark), true);
 }
 
 void
 Editor::clear_markers ()
 {
-       if (session) {
-               session->begin_reversible_command (_("clear markers"));
-                XMLNode &before = session->locations()->get_state();
-               session->locations()->clear_markers ();
-                XMLNode &after = session->locations()->get_state();
-               session->add_command(new MementoCommand<Locations>(*(session->locations()), &before, &after));
-               session->commit_reversible_command ();
+       if (_session) {
+               _session->begin_reversible_command (_("clear markers"));
+                XMLNode &before = _session->locations()->get_state();
+               _session->locations()->clear_markers ();
+                XMLNode &after = _session->locations()->get_state();
+               _session->add_command(new MementoCommand<Locations>(*(_session->locations()), &before, &after));
+               _session->commit_reversible_command ();
        }
 }
 
 void
 Editor::clear_ranges ()
 {
-       if (session) {
-               session->begin_reversible_command (_("clear ranges"));
-                XMLNode &before = session->locations()->get_state();
+       if (_session) {
+               _session->begin_reversible_command (_("clear ranges"));
+                XMLNode &before = _session->locations()->get_state();
 
-               Location * looploc = session->locations()->auto_loop_location();
-               Location * punchloc = session->locations()->auto_punch_location();
+               Location * looploc = _session->locations()->auto_loop_location();
+               Location * punchloc = _session->locations()->auto_punch_location();
 
-               session->locations()->clear_ranges ();
+               _session->locations()->clear_ranges ();
                // re-add these
-               if (looploc) session->locations()->add (looploc);
-               if (punchloc) session->locations()->add (punchloc);
+               if (looploc) _session->locations()->add (looploc);
+               if (punchloc) _session->locations()->add (punchloc);
 
-                XMLNode &after = session->locations()->get_state();
-               session->add_command(new MementoCommand<Locations>(*(session->locations()), &before, &after));
-               session->commit_reversible_command ();
+                XMLNode &after = _session->locations()->get_state();
+               _session->add_command(new MementoCommand<Locations>(*(_session->locations()), &before, &after));
+               _session->commit_reversible_command ();
        }
 }
 
 void
 Editor::clear_locations ()
 {
-       session->begin_reversible_command (_("clear locations"));
-        XMLNode &before = session->locations()->get_state();
-       session->locations()->clear ();
-        XMLNode &after = session->locations()->get_state();
-       session->add_command(new MementoCommand<Locations>(*(session->locations()), &before, &after));
-       session->commit_reversible_command ();
-       session->locations()->clear ();
+       _session->begin_reversible_command (_("clear locations"));
+        XMLNode &before = _session->locations()->get_state();
+       _session->locations()->clear ();
+        XMLNode &after = _session->locations()->get_state();
+       _session->add_command(new MementoCommand<Locations>(*(_session->locations()), &before, &after));
+       _session->commit_reversible_command ();
+       _session->locations()->clear ();
 }
 
 void
@@ -2251,9 +2228,9 @@ Editor::insert_region_list_drag (boost::shared_ptr<Region> region, int x, int y)
        snap_to (where);
 
        begin_reversible_command (_("insert dragged region"));
-        XMLNode &before = playlist->get_state();
+        playlist->clear_history ();
        playlist->add_region (RegionFactory::create (region), where, 1.0);
-       session->add_command(new MementoCommand<Playlist>(*playlist, &before, &playlist->get_state()));
+       _session->add_command(new StatefulDiffCommand (playlist));
        commit_reversible_command ();
 }
 
@@ -2329,9 +2306,9 @@ Editor::insert_region_list_selection (float times)
        }
 
        begin_reversible_command (_("insert region"));
-       XMLNode &before = playlist->get_state();
+        playlist->clear_history ();
        playlist->add_region ((RegionFactory::create (region)), get_preferred_edit_position(), times);
-       session->add_command(new MementoCommand<Playlist>(*playlist, &before, &playlist->get_state()));
+       _session->add_command(new StatefulDiffCommand (playlist));
        commit_reversible_command ();
 }
 
@@ -2355,68 +2332,38 @@ Editor::edit_envelope ()
 void
 Editor::transition_to_rolling (bool fwd)
 {
-       if (!session) {
+       if (!_session) {
                return;
        }
 
-       switch (Config->get_slave_source()) {
-       case None:
-       case JACK:
-               break;
-       default:
-               /* transport controlled by the master */
-               return;
-       }
-
-       if (session->is_auditioning()) {
-               session->cancel_audition ();
-               return;
-       }
-
-       session->request_transport_speed (fwd ? 1.0f : -1.0f);
-}
-
-void
-Editor::toggle_playback (bool with_abort)
-{
-       if (!session) {
-               return;
-       }
-
-       switch (Config->get_slave_source()) {
-       case None:
-       case JACK:
-               break;
-       default:
-               /* transport controlled by the master */
-               return;
+       if (_session->config.get_external_sync()) {
+               switch (_session->config.get_sync_source()) {
+               case JACK:
+                       break;
+               default:
+                       /* transport controlled by the master */
+                       return;
+               }
        }
 
-       if (session->is_auditioning()) {
-               session->cancel_audition ();
+       if (_session->is_auditioning()) {
+               _session->cancel_audition ();
                return;
        }
 
-       if (session->transport_rolling()) {
-               session->request_stop (with_abort);
-               if (session->get_play_loop()) {
-                       session->request_play_loop (false);
-               }
-       } else {
-               session->request_transport_speed (1.0f);
-       }
+       _session->request_transport_speed (fwd ? 1.0f : -1.0f);
 }
 
 void
 Editor::play_from_start ()
 {
-       session->request_locate (session->current_start_frame(), true);
+       _session->request_locate (_session->current_start_frame(), true);
 }
 
 void
 Editor::play_from_edit_point ()
 {
-       session->request_locate (get_preferred_edit_position(), true);
+       _session->request_locate (get_preferred_edit_position(), true);
 }
 
 void
@@ -2427,19 +2374,19 @@ Editor::play_from_edit_point_and_return ()
 
        start_frame = get_preferred_edit_position (true);
 
-       if (session->transport_rolling()) {
-               session->request_locate (start_frame, false);
+       if (_session->transport_rolling()) {
+               _session->request_locate (start_frame, false);
                return;
        }
 
        /* don't reset the return frame if its already set */
 
-       if ((return_frame = session->requested_return_frame()) < 0) {
-               return_frame = session->audible_frame();
+       if ((return_frame = _session->requested_return_frame()) < 0) {
+               return_frame = _session->audible_frame();
        }
 
        if (start_frame >= 0) {
-               session->request_roll_at_and_return (start_frame, return_frame);
+               _session->request_roll_at_and_return (start_frame, return_frame);
        }
 }
 
@@ -2450,7 +2397,7 @@ Editor::play_selection ()
                return;
        }
 
-       session->request_play_range (true);
+       _session->request_play_range (&selection->time, true);
 }
 
 void
@@ -2470,9 +2417,9 @@ Editor::loop_selected_region ()
 
                        // enable looping, reposition and start rolling
 
-                       session->request_play_loop (true);
-                       session->request_locate (tll->start(), false);
-                       session->request_transport_speed (1.0f);
+                       _session->request_play_loop (true);
+                       _session->request_locate (tll->start(), false);
+                       _session->request_transport_speed (1.0f);
                }
        }
 }
@@ -2484,7 +2431,7 @@ Editor::play_location (Location& location)
                return;
        }
 
-       session->request_bounded_roll (location.start(), location.end());
+       _session->request_bounded_roll (location.start(), location.end());
 }
 
 void
@@ -2500,8 +2447,8 @@ Editor::loop_location (Location& location)
                tll->set (location.start(), location.end());
 
                // enable looping, reposition and start rolling
-               session->request_play_loop (true);
-               session->request_locate (tll->start(), true);
+               _session->request_play_loop (true);
+               _session->request_locate (tll->start(), true);
        }
 }
 
@@ -2554,10 +2501,7 @@ Editor::rename_region()
                return;
        }
 
-       WindowTitle title (Glib::get_application_name());
-       title += _("Rename Region");
-
-       ArdourDialog d (*this, title.get_string(), true, false);
+       ArdourDialog d (*this, _("Rename Region"), true, false);
        Entry entry;
        Label label (_("New name:"));
        HBox hbox;
@@ -2569,8 +2513,8 @@ Editor::rename_region()
        d.get_vbox()->set_border_width (12);
        d.get_vbox()->pack_start (hbox, false, false);
 
-       d.add_button(Gtk::Stock::OK, Gtk::RESPONSE_OK);
        d.add_button(Gtk::Stock::CANCEL, Gtk::RESPONSE_CANCEL);
+       d.add_button(Gtk::Stock::OK, Gtk::RESPONSE_OK);
 
        d.set_size_request (300, -1);
        d.set_position (Gtk::WIN_POS_MOUSE);
@@ -2578,7 +2522,7 @@ Editor::rename_region()
        entry.set_text (rs.front()->region()->name());
        entry.select_region (0, -1);
 
-       entry.signal_activate().connect (bind (mem_fun (d, &Dialog::response), RESPONSE_OK));
+       entry.signal_activate().connect (sigc::bind (sigc::mem_fun (d, &Dialog::response), RESPONSE_OK));
 
        d.show_all ();
 
@@ -2601,8 +2545,8 @@ Editor::rename_region()
 void
 Editor::audition_playlist_region_via_route (boost::shared_ptr<Region> region, Route& route)
 {
-       if (session->is_auditioning()) {
-               session->cancel_audition ();
+       if (_session->is_auditioning()) {
+               _session->cancel_audition ();
        }
 
        // note: some potential for creativity here, because region doesn't
@@ -2612,7 +2556,7 @@ Editor::audition_playlist_region_via_route (boost::shared_ptr<Region> region, Ro
 
        route.set_solo (true, this);
 
-       session->request_bounded_roll (region->position(), region->position() + region->length());
+       _session->request_bounded_roll (region->position(), region->position() + region->length());
 
        /* XXX how to unset the solo state ? */
 }
@@ -2624,7 +2568,7 @@ Editor::play_edit_range ()
        nframes64_t start, end;
 
        if (get_edit_op_range (start, end)) {
-               session->request_bounded_roll (start, end);
+               _session->request_bounded_roll (start, end);
        }
 }
 
@@ -2650,47 +2594,13 @@ Editor::play_selected_region ()
                }
        }
 
-       session->request_stop ();
-       session->request_bounded_roll (start, end);
+       _session->request_bounded_roll (start, end);
 }
 
 void
 Editor::audition_playlist_region_standalone (boost::shared_ptr<Region> region)
 {
-       session->audition_region (region);
-}
-
-void
-Editor::build_interthread_progress_window ()
-{
-       interthread_progress_window = new ArdourDialog (X_("interthread progress"), true);
-
-       interthread_progress_bar.set_orientation (Gtk::PROGRESS_LEFT_TO_RIGHT);
-
-       interthread_progress_window->set_border_width (12);
-       interthread_progress_window->get_vbox()->set_spacing (6);
-
-       interthread_progress_label.set_alignment (0.5, 0.5);
-
-       interthread_progress_window->get_vbox()->pack_start (interthread_progress_label, false, false);
-       interthread_progress_window->get_vbox()->pack_start (interthread_progress_bar,false, false);
-
-       // GTK2FIX: this button needs a modifiable label
-
-       Button* b = interthread_progress_window->add_button (Stock::CANCEL, RESPONSE_CANCEL);
-       b->signal_clicked().connect (mem_fun(*this, &Editor::interthread_cancel_clicked));
-
-       interthread_cancel_button.add (interthread_cancel_label);
-
-       interthread_progress_window->set_default_size (200, 100);
-}
-
-void
-Editor::interthread_cancel_clicked ()
-{
-       if (current_interthread_info) {
-               current_interthread_info->cancel = true;
-       }
+       _session->audition_region (region);
 }
 
 void
@@ -2707,7 +2617,7 @@ Editor::region_from_selection ()
        nframes64_t start = selection->time[clicked_selection].start;
        nframes64_t end = selection->time[clicked_selection].end;
 
-       TrackSelection tracks = get_tracks_for_range_action ();
+       TrackViewList tracks = get_tracks_for_range_action ();
 
        nframes64_t selection_cnt = end - start + 1;
 
@@ -2726,9 +2636,16 @@ Editor::region_from_selection ()
                }
 
                internal_start = start - current->position();
-               session->region_name (new_name, current->name(), true);
-               boost::shared_ptr<Region> region (RegionFactory::create (current,
-                               internal_start, selection_cnt, new_name));
+               RegionFactory::region_name (new_name, current->name(), true);
+
+               PropertyList plist; 
+               
+               plist.add (ARDOUR::Properties::start, current->start() + internal_start);
+               plist.add (ARDOUR::Properties::length, selection_cnt);
+               plist.add (ARDOUR::Properties::name, new_name);
+               plist.add (ARDOUR::Properties::layer, 0);
+
+               boost::shared_ptr<Region> region (RegionFactory::create (current, plist));
        }
 }
 
@@ -2759,10 +2676,15 @@ Editor::create_region_from_selection (vector<boost::shared_ptr<Region> >& new_re
                }
 
                internal_start = start - current->position();
-               session->region_name (new_name, current->name(), true);
+               RegionFactory::region_name (new_name, current->name(), true);
 
-               new_regions.push_back (RegionFactory::create (current,
-                                       internal_start, end - start + 1, new_name));
+               PropertyList plist; 
+               
+               plist.add (ARDOUR::Properties::start, current->start() + internal_start);
+               plist.add (ARDOUR::Properties::length, end - start + 1);
+               plist.add (ARDOUR::Properties::name, new_name);
+
+               new_regions.push_back (RegionFactory::create (current, plist));
        }
 }
 
@@ -2780,7 +2702,7 @@ Editor::split_multichannel_region ()
        vector< boost::shared_ptr<Region> > v;
 
        for (list<RegionView*>::iterator x = rs.begin(); x != rs.end(); ++x) {
-               (*x)->region()->separate_by_channel (*session, v);
+               (*x)->region()->separate_by_channel (*_session, v);
        }
 }
 
@@ -2808,10 +2730,10 @@ add_if_covered (RegionView* rv, const AudioRange* ar, RegionSelection* rs)
  *    - all tracks
  * @return tracks.
  */
-TrackSelection
+TrackViewList
 Editor::get_tracks_for_range_action () const
 {
-       TrackSelection t;
+       TrackViewList t;
 
        if (selection->tracks.empty()) {
 
@@ -2847,7 +2769,7 @@ Editor::separate_regions_between (const TimeSelection& ts)
        boost::shared_ptr<Playlist> playlist;
        RegionSelection new_selection;
 
-       TrackSelection tmptracks = get_tracks_for_range_action ();
+       TrackViewList tmptracks = get_tracks_for_range_action ();
        sort_track_selection (&tmptracks);
 
        for (TrackSelection::iterator i = tmptracks.begin(); i != tmptracks.end(); ++i) {
@@ -2860,27 +2782,23 @@ Editor::separate_regions_between (const TimeSelection& ts)
 
                                /* no edits to destructive tracks */
 
-                               if (rtv->track()->diskstream()->destructive()) {
+                               if (rtv->track()->destructive()) {
                                        continue;
                                }
 
                                if ((playlist = rtv->playlist()) != 0) {
 
-                                       XMLNode *before;
-                                       bool got_some;
-
-                                       before = &(playlist->get_state());
-                                       got_some = false;
+                                       playlist->clear_history ();
 
                                        /* XXX need to consider musical time selections here at some point */
 
-                                       double speed = rtv->get_diskstream()->speed();
+                                       double speed = rtv->track()->speed();
 
 
                                        for (list<AudioRange>::const_iterator t = ts.begin(); t != ts.end(); ++t) {
 
                                                sigc::connection c = rtv->view()->RegionViewAdded.connect (
-                                                               mem_fun(*this, &Editor::collect_new_region_view));
+                                                               sigc::mem_fun(*this, &Editor::collect_new_region_view));
                                                latest_regionviews.clear ();
 
                                                playlist->partition ((nframes64_t)((*t).start * speed),
@@ -2890,25 +2808,18 @@ Editor::separate_regions_between (const TimeSelection& ts)
 
                                                if (!latest_regionviews.empty()) {
 
-                                                       got_some = true;
-
-                                                       rtv->view()->foreach_regionview (bind (
+                                                       rtv->view()->foreach_regionview (sigc::bind (
                                                                                sigc::ptr_fun (add_if_covered),
                                                                                &(*t), &new_selection));
-
+                                                        
                                                        if (!in_command) {
                                                                begin_reversible_command (_("separate"));
                                                                in_command = true;
                                                        }
 
-                                                       session->add_command(new MementoCommand<Playlist>(
-                                                                       *playlist, before, &playlist->get_state()));
+                                                       _session->add_command(new StatefulDiffCommand (playlist));
                                                }
                                        }
-
-                                       if (!got_some) {
-                                               delete before;
-                                       }
                                }
                        }
                }
@@ -2957,7 +2868,7 @@ Editor::separate_region_from_selection ()
 void
 Editor::separate_region_from_punch ()
 {
-       Location* loc  = session->locations()->auto_punch_location();
+       Location* loc  = _session->locations()->auto_punch_location();
        if (loc) {
                separate_regions_using_location (*loc);
        }
@@ -2966,7 +2877,7 @@ Editor::separate_region_from_punch ()
 void
 Editor::separate_region_from_loop ()
 {
-       Location* loc  = session->locations()->auto_loop_location();
+       Location* loc  = _session->locations()->auto_loop_location();
        if (loc) {
                separate_regions_using_location (*loc);
        }
@@ -3011,7 +2922,7 @@ Editor::crop_region_to (nframes64_t start, nframes64_t end)
 {
        vector<boost::shared_ptr<Playlist> > playlists;
        boost::shared_ptr<Playlist> playlist;
-       TrackSelection* ts;
+       TrackViewList* ts;
 
        if (selection->tracks.empty()) {
                ts = &track_views;
@@ -3028,7 +2939,7 @@ Editor::crop_region_to (nframes64_t start, nframes64_t end)
 
                        boost::shared_ptr<Track> t = rtv->track();
 
-                       if (t != 0 && ! t->diskstream()->destructive()) {
+                       if (t != 0 && ! t->destructive()) {
 
                                if ((playlist = rtv->playlist()) != 0) {
                                        playlists.push_back (playlist);
@@ -3070,10 +2981,9 @@ Editor::crop_region_to (nframes64_t start, nframes64_t end)
                the_end = min (end, the_end);
                cnt = the_end - the_start + 1;
 
-               XMLNode &before = (*i)->get_state();
+                region->clear_history ();
                region->trim_to (the_start, cnt, this);
-               XMLNode &after = (*i)->get_state();
-               session->add_command (new MementoCommand<Playlist>(*(*i), &before, &after));
+               _session->add_command (new StatefulDiffCommand (region));
        }
 
        commit_reversible_command ();
@@ -3087,11 +2997,11 @@ Editor::region_fill_track ()
 
        get_regions_for_action (rs);
 
-       if (!session || rs.empty()) {
+       if (!_session || rs.empty()) {
                return;
        }
 
-       end = session->current_end_frame ();
+       end = _session->current_end_frame ();
 
        begin_reversible_command (_("region fill"));
 
@@ -3099,10 +3009,6 @@ Editor::region_fill_track ()
 
                boost::shared_ptr<Region> region ((*i)->region());
 
-               // FIXME
-               boost::shared_ptr<AudioRegion> ar = boost::dynamic_pointer_cast<AudioRegion>(region);
-               assert(ar);
-
                boost::shared_ptr<Playlist> pl = region->playlist();
 
                if (end <= region->last_frame()) {
@@ -3115,9 +3021,9 @@ Editor::region_fill_track ()
                        return;
                }
 
-               XMLNode &before = pl->get_state();
-               pl->add_region (RegionFactory::create (ar), ar->last_frame(), times);
-               session->add_command (new MementoCommand<Playlist>(*pl, &before, &pl->get_state()));
+                pl->clear_history ();
+               pl->add_region (RegionFactory::create (region), region->last_frame(), times);
+               _session->add_command (new StatefulDiffCommand (pl));
        }
 
        commit_reversible_command ();
@@ -3126,7 +3032,7 @@ Editor::region_fill_track ()
 void
 Editor::region_fill_selection ()
 {
-       if (clicked_routeview == 0 || !clicked_routeview->is_audio_track()) {
+       if (clicked_routeview == 0 || !clicked_routeview->is_audio_track()) {
                return;
        }
 
@@ -3159,9 +3065,9 @@ Editor::region_fill_selection ()
                        continue;
                }
 
-                XMLNode &before = playlist->get_state();
+                playlist->clear_history ();
                playlist->add_region (RegionFactory::create (region), start, times);
-               session->add_command (new MementoCommand<Playlist>(*playlist, &before, &playlist->get_state()));
+               _session->add_command (new StatefulDiffCommand (playlist));
        }
 
        commit_reversible_command ();
@@ -3194,10 +3100,9 @@ Editor::set_sync_point (nframes64_t where, const RegionSelection& rs)
                        in_command = true;
                }
 
-               XMLNode &before = region->playlist()->get_state();
-               region->set_sync_position (get_preferred_edit_position());
-               XMLNode &after = region->playlist()->get_state();
-               session->add_command(new MementoCommand<Playlist>(*(region->playlist()), &before, &after));
+                region->clear_history ();
+               region->set_sync_position (where);
+               _session->add_command(new StatefulDiffCommand (region));
        }
 
        if (in_command) {
@@ -3220,10 +3125,9 @@ Editor::remove_region_sync ()
        begin_reversible_command (_("remove sync"));
        for (RegionSelection::iterator i = rs.begin(); i != rs.end(); ++i) {
 
-                XMLNode &before = (*i)->region()->playlist()->get_state();
+                (*i)->region()->clear_history ();
                (*i)->region()->clear_sync_position ();
-                XMLNode &after = (*i)->region()->playlist()->get_state();
-               session->add_command(new MementoCommand<Playlist>(*((*i)->region()->playlist()), &before, &after));
+               _session->add_command(new StatefulDiffCommand ((*i)->region()));
        }
        commit_reversible_command ();
 }
@@ -3241,10 +3145,9 @@ Editor::naturalize ()
 
        begin_reversible_command (_("naturalize"));
        for (RegionSelection::iterator i = rs.begin(); i != rs.end(); ++i) {
-                XMLNode &before = (*i)->region()->get_state();
+               (*i)->region()->clear_history ();
                (*i)->region()->move_to_natural_position (this);
-                XMLNode &after = (*i)->region()->get_state();
-               session->add_command (new MementoCommand<Region>(*((*i)->region().get()), &before, &after));
+               _session->add_command (new StatefulDiffCommand ((*i)->region()));
        }
        commit_reversible_command ();
 }
@@ -3343,10 +3246,9 @@ Editor::align_selection_relative (RegionPoint point, nframes64_t position, const
 
        /* move first one specially */
 
-       XMLNode &before = r->playlist()->get_state();
+        r->clear_history ();
        r->set_position (pos, this);
-       XMLNode &after = r->playlist()->get_state();
-       session->add_command(new MementoCommand<Playlist>(*(r->playlist()), &before, &after));
+       _session->add_command(new StatefulDiffCommand (r));
 
        /* move rest by the same amount */
 
@@ -3356,16 +3258,15 @@ Editor::align_selection_relative (RegionPoint point, nframes64_t position, const
 
                boost::shared_ptr<Region> region ((*i)->region());
 
-                XMLNode &before = region->playlist()->get_state();
+                region->clear_history ();
 
                if (dir > 0) {
                        region->set_position (region->position() + distance, this);
                } else {
                        region->set_position (region->position() - distance, this);
                }
-
-                XMLNode &after = region->playlist()->get_state();
-               session->add_command(new MementoCommand<Playlist>(*(region->playlist()), &before, &after));
+                
+               _session->add_command(new StatefulDiffCommand (region));
 
        }
 
@@ -3399,7 +3300,7 @@ Editor::align_region (boost::shared_ptr<Region> region, RegionPoint point, nfram
 void
 Editor::align_region_internal (boost::shared_ptr<Region> region, RegionPoint point, nframes64_t position)
 {
-       XMLNode &before = region->playlist()->get_state();
+       region->clear_history ();
 
        switch (point) {
        case SyncPoint:
@@ -3417,8 +3318,7 @@ Editor::align_region_internal (boost::shared_ptr<Region> region, RegionPoint poi
                break;
        }
 
-       XMLNode &after = region->playlist()->get_state();
-       session->add_command(new MementoCommand<Playlist>(*(region->playlist()), &before, &after));
+       _session->add_command(new StatefulDiffCommand (region));
 }
 
 void
@@ -3449,15 +3349,13 @@ Editor::trim_region (bool front)
 
        for (list<RegionView*>::const_iterator i = rs.by_layer().begin(); i != rs.by_layer().end(); ++i) {
                if (!(*i)->region()->locked()) {
-                       boost::shared_ptr<Playlist> pl = (*i)->region()->playlist();
-                       XMLNode &before = pl->get_state();
+                        (*i)->region()->clear_history ();
                        if (front) {
                                (*i)->region()->trim_front (where, this);
                        } else {
                                (*i)->region()->trim_end (where, this);
                        }
-                       XMLNode &after = pl->get_state();
-                       session->add_command(new MementoCommand<Playlist>(*pl.get(), &before, &after));
+                       _session->add_command (new StatefulDiffCommand ((*i)->region()));
                }
        }
 
@@ -3468,7 +3366,7 @@ Editor::trim_region (bool front)
 void
 Editor::trim_region_to_loop ()
 {
-       Location* loc = session->locations()->auto_loop_location();
+       Location* loc = _session->locations()->auto_loop_location();
        if (!loc) {
                return;
        }
@@ -3478,7 +3376,7 @@ Editor::trim_region_to_loop ()
 void
 Editor::trim_region_to_punch ()
 {
-       Location* loc = session->locations()->auto_punch_location();
+       Location* loc = _session->locations()->auto_punch_location();
        if (!loc) {
                return;
        }
@@ -3513,18 +3411,16 @@ Editor::trim_region_to_location (const Location& loc, const char* str)
                nframes64_t start;
                nframes64_t end;
 
-               if (tav->get_diskstream() != 0) {
-                       speed = tav->get_diskstream()->speed();
+               if (tav->track() != 0) {
+                       speed = tav->track()->speed();
                }
 
                start = session_frame_to_track_frame (loc.start(), speed);
                end = session_frame_to_track_frame (loc.end(), speed);
-
-               XMLNode &before = rv->region()->playlist()->get_state();
+                
+               rv->region()->clear_history ();
                rv->region()->trim_to (start, (end - start), this);
-               XMLNode &after = rv->region()->playlist()->get_state();
-               session->add_command(new MementoCommand<Playlist>(
-                               *(rv->region()->playlist()), &before, &after));
+               _session->add_command(new StatefulDiffCommand (rv->region()));
        }
 
        commit_reversible_command ();
@@ -3556,15 +3452,13 @@ Editor::trim_region_to_edit_point ()
 
                float speed = 1.0;
 
-               if (tav->get_diskstream() != 0) {
-                       speed = tav->get_diskstream()->speed();
+               if (tav->track() != 0) {
+                       speed = tav->track()->speed();
                }
 
-               XMLNode &before = rv->region()->playlist()->get_state();
-               rv->region()->trim_end( session_frame_to_track_frame(where, speed), this);
-               XMLNode &after = rv->region()->playlist()->get_state();
-               session->add_command(new MementoCommand<Playlist>(
-                               *(rv->region()->playlist()), &before, &after));
+                rv->region()->clear_history ();
+               rv->region()->trim_end (session_frame_to_track_frame(where, speed), this);
+               _session->add_command(new StatefulDiffCommand (rv->region()));
        }
 
        commit_reversible_command ();
@@ -3596,15 +3490,13 @@ Editor::trim_region_from_edit_point ()
 
                float speed = 1.0;
 
-               if (tav->get_diskstream() != 0) {
-                       speed = tav->get_diskstream()->speed();
+               if (tav->track() != 0) {
+                       speed = tav->track()->speed();
                }
 
-               XMLNode &before = rv->region()->playlist()->get_state();
-               rv->region()->trim_front ( session_frame_to_track_frame(where, speed), this);
-               XMLNode &after = rv->region()->playlist()->get_state();
-               session->add_command(new MementoCommand<Playlist>(
-                               *(rv->region()->playlist()), &before, &after));
+                rv->region()->clear_history ();
+               rv->region()->trim_front (session_frame_to_track_frame(where, speed), this);
+               _session->add_command(new StatefulDiffCommand (rv->region()));
        }
 
        commit_reversible_command ();
@@ -3649,15 +3541,15 @@ Editor::trim_to_region(bool forward)
 
                float speed = 1.0;
 
-               if (atav->get_diskstream() != 0) {
-                       speed = atav->get_diskstream()->speed();
+               if (atav->track() != 0) {
+                       speed = atav->track()->speed();
                }
 
 
                boost::shared_ptr<Region> region = arv->region();
                boost::shared_ptr<Playlist> playlist (region->playlist());
 
-               XMLNode &before = playlist->get_state();
+                region->clear_history ();
 
                if(forward){
 
@@ -3668,7 +3560,7 @@ Editor::trim_to_region(bool forward)
                    }
 
                    region->trim_end((nframes64_t) (next_region->first_frame() * speed), this);
-                   arv->region_changed (Change (LengthChanged));
+                   arv->region_changed (PropertyChange (ARDOUR::Properties::length));
                }
                else {
 
@@ -3679,11 +3571,11 @@ Editor::trim_to_region(bool forward)
                    }
 
                    region->trim_front((nframes64_t) ((next_region->last_frame() + 1) * speed), this);
-                   arv->region_changed (Change (LengthChanged|PositionChanged|StartChanged));
+
+                   arv->region_changed (ARDOUR::bounds_change);
                }
 
-               XMLNode &after = playlist->get_state();
-               session->add_command(new MementoCommand<Playlist>(*playlist, &before, &after));
+               _session->add_command(new StatefulDiffCommand (region));
        }
 
        commit_reversible_command ();
@@ -3702,25 +3594,19 @@ Editor::unfreeze_route ()
 void*
 Editor::_freeze_thread (void* arg)
 {
-       PBD::notify_gui_about_thread_creation (pthread_self(), X_("Freeze"));
+       SessionEvent::create_per_thread_pool ("freeze events", 64);
+
        return static_cast<Editor*>(arg)->freeze_thread ();
 }
 
 void*
 Editor::freeze_thread ()
 {
-       clicked_routeview->audio_track()->freeze (*current_interthread_info);
+       clicked_routeview->audio_track()->freeze_me (*current_interthread_info);
        current_interthread_info->done = true;
        return 0;
 }
 
-gint
-Editor::freeze_progress_timeout (void */*arg*/)
-{
-       interthread_progress_bar.set_fraction (current_interthread_info->progress);
-       return !(current_interthread_info->done || current_interthread_info->cancel);
-}
-
 void
 Editor::freeze_route ()
 {
@@ -3729,35 +3615,15 @@ Editor::freeze_route ()
        }
 
        InterThreadInfo itt;
-
-       if (interthread_progress_window == 0) {
-               build_interthread_progress_window ();
-       }
-
-       WindowTitle title(Glib::get_application_name());
-       title += _("Freeze");
-       interthread_progress_window->set_title (title.get_string());
-       interthread_progress_window->set_position (Gtk::WIN_POS_MOUSE);
-       interthread_progress_window->show_all ();
-       interthread_progress_bar.set_fraction (0.0f);
-       interthread_progress_label.set_text ("");
-       interthread_cancel_label.set_text (_("Cancel Freeze"));
        current_interthread_info = &itt;
 
-       interthread_progress_connection =
-         Glib::signal_timeout().connect (bind (mem_fun(*this, &Editor::freeze_progress_timeout), (gpointer) 0), 100);
+       InterthreadProgressWindow ipw (current_interthread_info, _("Freeze"), _("Cancel Freeze"));
 
        itt.done = false;
        itt.cancel = false;
        itt.progress = 0.0f;
 
-       pthread_attr_t attr;
-       pthread_attr_init(&attr);
-       pthread_attr_setstacksize(&attr, 500000);
-
-       pthread_create_and_store (X_("freezer"), &itt.thread, &attr, _freeze_thread, this);
-
-       pthread_attr_destroy(&attr);
+       pthread_create_and_store (X_("freezer"), &itt.thread, _freeze_thread, this);
 
        track_canvas->get_window()->set_cursor (Gdk::Cursor (Gdk::WATCH));
 
@@ -3765,8 +3631,6 @@ Editor::freeze_route ()
                gtk_main_iteration ();
        }
 
-       interthread_progress_connection.disconnect ();
-       interthread_progress_window->hide_all ();
        current_interthread_info = 0;
        track_canvas->get_window()->set_cursor (*current_canvas_cursor);
 }
@@ -3806,7 +3670,7 @@ Editor::bounce_range_selection (bool replace, bool enable_processing)
                itt.cancel = false;
                itt.progress = false;
 
-                XMLNode &before = playlist->get_state();
+                playlist->clear_history ();
                boost::shared_ptr<Region> r = rtv->track()->bounce_range (start, start+cnt, itt, enable_processing);
 
                if (replace) {
@@ -3816,8 +3680,7 @@ Editor::bounce_range_selection (bool replace, bool enable_processing)
                        playlist->add_region (r, start);
                }
 
-                XMLNode &after = playlist->get_state();
-               session->add_command (new MementoCommand<Playlist> (*playlist, &before, &after));
+               _session->add_command (new StatefulDiffCommand (playlist));
        }
 
        commit_reversible_command ();
@@ -3893,10 +3756,8 @@ Editor::cut_copy (CutCopyOp op)
        */
 
        if (op == Cut || op == Clear) {
-               if (_drag) {
-                       _drag->item()->ungrab (0);
-                       delete _drag;
-                       _drag = 0;
+               if (_drags->active ()) {
+                       _drags->abort ();
                }
        }
 
@@ -3909,14 +3770,11 @@ Editor::cut_copy (CutCopyOp op)
                bool ignored;
                Location* loc = find_location_from_marker (entered_marker, ignored);
 
-               if (session && loc) {
-                       Glib::signal_idle().connect (bind (mem_fun(*this, &Editor::really_remove_marker), loc));
+               if (_session && loc) {
+                       Glib::signal_idle().connect (sigc::bind (sigc::mem_fun(*this, &Editor::really_remove_marker), loc));
                }
 
-               break_drag ();
-               delete _drag;
-               _drag = 0;
-
+               _drags->break_drag ();
                return;
        }
 
@@ -3978,7 +3836,7 @@ Editor::cut_copy (CutCopyOp op)
                                if (!get_edit_op_range (start, end)) {
                                        return;
                                }
-                               selection->set ((TimeAxisView*) 0, start, end);
+                               selection->set (start, end);
                        }
 
                        begin_reversible_command (opname + _(" range"));
@@ -3997,9 +3855,7 @@ Editor::cut_copy (CutCopyOp op)
        }
 
        if (op == Cut || op == Clear) {
-               break_drag ();
-               delete _drag;
-               _drag = 0;
+               _drags->break_drag ();
        }
 }
 
@@ -4011,7 +3867,7 @@ Editor::cut_copy_points (CutCopyOp op)
 {
        for (PointSelection::iterator i = selection->points.begin(); i != selection->points.end(); ++i) {
 
-               AutomationTimeAxisView* atv = dynamic_cast<AutomationTimeAxisView*>(&(*i).track);
+               AutomationTimeAxisView* atv = dynamic_cast<AutomationTimeAxisView*>((*i).track);
 
                if (atv) {
                        atv->cut_copy_clear_objects (selection->points, op);
@@ -4031,17 +3887,6 @@ Editor::cut_copy_midi (CutCopyOp op)
        }
 }
 
-struct PlaylistState {
-    boost::shared_ptr<Playlist> playlist;
-    XMLNode*  before;
-};
-
-struct lt_playlist {
-    bool operator () (const PlaylistState& a, const PlaylistState& b) {
-           return a.playlist < b.playlist;
-    }
-};
-
 struct PlaylistMapping {
     TimeAxisView* tv;
     boost::shared_ptr<Playlist> pl;
@@ -4060,10 +3905,9 @@ Editor::remove_clicked_region ()
        boost::shared_ptr<Playlist> playlist = clicked_routeview->playlist();
 
        begin_reversible_command (_("remove region"));
-        XMLNode &before = playlist->get_state();
+        playlist->clear_history ();
        playlist->remove_region (clicked_regionview->region());
-        XMLNode &after = playlist->get_state();
-       session->add_command(new MementoCommand<Playlist>(*playlist, &before, &after));
+       _session->add_command(new StatefulDiffCommand (playlist));
        commit_reversible_command ();
 }
 
@@ -4075,7 +3919,7 @@ Editor::remove_selected_regions ()
        RegionSelection rs;
        get_regions_for_action (rs);
 
-       if (!session) {
+       if (!_session) {
                return;
        }
 
@@ -4100,7 +3944,7 @@ Editor::remove_selected_regions ()
                regions_to_remove.push_back ((*i)->region());
        }
 
-       vector<PlaylistState> playlists;
+        vector<boost::shared_ptr<Playlist> > playlists;
 
        for (list<boost::shared_ptr<Region> >::iterator rl = regions_to_remove.begin(); rl != regions_to_remove.end(); ++rl) {
 
@@ -4111,33 +3955,31 @@ Editor::remove_selected_regions ()
                        continue;
                }
 
-               vector<PlaylistState>::iterator i;
+               vector<boost::shared_ptr<Playlist> >::iterator i;
 
-               //only take state if this is a new playlist.
+               //only prep history if this is a new playlist.
                for (i = playlists.begin(); i != playlists.end(); ++i) {
-                       if ((*i).playlist == playlist) {
+                       if ((*i) == playlist) {
                                break;
                        }
                }
 
                if (i == playlists.end()) {
 
-                       PlaylistState before;
-                       before.playlist = playlist;
-                       before.before = &playlist->get_state();
-
+                        playlist->clear_history ();
                        playlist->freeze ();
-                       playlists.push_back(before);
+
+                       playlists.push_back (playlist);
                }
 
                playlist->remove_region (*rl);
        }
 
-       vector<PlaylistState>::iterator pl;
+       vector<boost::shared_ptr<Playlist> >::iterator pl;
 
        for (pl = playlists.begin(); pl != playlists.end(); ++pl) {
-               (*pl).playlist->thaw ();
-               session->add_command(new MementoCommand<Playlist>(*(*pl).playlist, (*pl).before, &(*pl).playlist->get_state()));
+               (*pl)->thaw ();
+               _session->add_command(new StatefulDiffCommand (*pl));
        }
 
        commit_reversible_command ();
@@ -4157,8 +3999,8 @@ Editor::cut_copy_regions (CutCopyOp op, RegionSelection& rs)
 
        nframes64_t first_position = max_frames;
 
-       set<PlaylistState, lt_playlist> freezelist;
-       pair<set<PlaylistState, lt_playlist>::iterator,bool> insert_result;
+       typedef set<boost::shared_ptr<Playlist> > FreezeList;
+        FreezeList freezelist;
 
        /* get ordering correct before we cut/copy */
 
@@ -4172,21 +4014,19 @@ Editor::cut_copy_regions (CutCopyOp op, RegionSelection& rs)
                        boost::shared_ptr<Playlist> pl = (*x)->region()->playlist();
 
                        if (pl) {
-                               set<PlaylistState, lt_playlist>::iterator fl;
+                               FreezeList::iterator fl;
 
                                //only take state if this is a new playlist.
                                for (fl = freezelist.begin(); fl != freezelist.end(); ++fl) {
-                                       if ((*fl).playlist == pl) {
+                                       if ((*fl) == pl) {
                                                break;
                                        }
                                }
 
                                if (fl == freezelist.end()) {
-                                       PlaylistState before;
-                                       before.playlist = pl;
-                                       before.before = &pl->get_state();
+                                        pl->clear_history();
                                        pl->freeze ();
-                                       insert_result = freezelist.insert (before);
+                                       freezelist.insert (pl);
                                }
                        }
                }
@@ -4232,7 +4072,7 @@ Editor::cut_copy_regions (CutCopyOp op, RegionSelection& rs)
                assert (z != pmap.end());
 
                if (!(*z).pl) {
-                       npl = PlaylistFactory::create (pl->data_type(), *session, "cutlist", true);
+                       npl = PlaylistFactory::create (pl->data_type(), *_session, "cutlist", true);
                        npl->freeze();
                        (*z).pl = npl;
                } else {
@@ -4277,18 +4117,18 @@ Editor::cut_copy_regions (CutCopyOp op, RegionSelection& rs)
        if (!foo.empty()) {
                cut_buffer->set (foo);
        }
-
-       for (set<PlaylistState, lt_playlist>::iterator pl = freezelist.begin(); pl != freezelist.end(); ++pl) {
-               (*pl).playlist->thaw ();
-               session->add_command (new MementoCommand<Playlist>(*(*pl).playlist, (*pl).before, &(*pl).playlist->get_state()));
+        
+       for (FreezeList::iterator pl = freezelist.begin(); pl != freezelist.end(); ++pl) {
+               (*pl)->thaw ();
+               _session->add_command (new StatefulDiffCommand (*pl));
        }
 }
 
 void
 Editor::cut_copy_ranges (CutCopyOp op)
 {
-       TrackSelection* ts;
-       TrackSelection entered;
+       TrackViewList* ts;
+       TrackViewList entered;
 
        if (selection->tracks.empty()) {
                if (!entered_track) {
@@ -4346,8 +4186,8 @@ Editor::paste_internal (nframes64_t position, float times)
 
        begin_reversible_command (_("paste"));
 
-       TrackSelection ts;
-       TrackSelection::iterator i;
+       TrackViewList ts;
+       TrackViewList::iterator i;
        size_t nth;
 
        /* get everything in the correct order */
@@ -4393,62 +4233,6 @@ Editor::paste_internal (nframes64_t position, float times)
        }
 }
 
-void
-Editor::paste_named_selection (float times)
-{
-       TrackSelection::iterator t;
-
-       Glib::RefPtr<TreeSelection> selected = named_selection_display.get_selection();
-
-       if (selected->count_selected_rows() != 1 || selection->tracks.empty()) {
-               return;
-       }
-
-       TreeModel::iterator i = selected->get_selected();
-       NamedSelection* ns = (*i)[named_selection_columns.selection];
-
-       list<boost::shared_ptr<Playlist> >::iterator chunk;
-       list<boost::shared_ptr<Playlist> >::iterator tmp;
-
-       chunk = ns->playlists.begin();
-
-       begin_reversible_command (_("paste chunk"));
-
-       sort_track_selection ();
-
-       for (t = selection->tracks.begin(); t != selection->tracks.end(); ++t) {
-
-               RouteTimeAxisView* rtv;
-               boost::shared_ptr<Playlist> pl;
-               boost::shared_ptr<AudioPlaylist> apl;
-
-               if ((rtv = dynamic_cast<RouteTimeAxisView*> (*t)) == 0) {
-                       continue;
-               }
-
-               if ((pl = rtv->playlist()) == 0) {
-                       continue;
-               }
-
-               if ((apl = boost::dynamic_pointer_cast<AudioPlaylist> (pl)) == 0) {
-                       continue;
-               }
-
-               tmp = chunk;
-               ++tmp;
-
-               XMLNode &before = apl->get_state();
-               apl->paste (*chunk, get_preferred_edit_position(), times);
-               session->add_command(new MementoCommand<AudioPlaylist>(*apl, &before, &apl->get_state()));
-
-               if (tmp != ns->playlists.end()) {
-                       chunk = tmp;
-               }
-       }
-
-       commit_reversible_command();
-}
-
 void
 Editor::duplicate_some_regions (RegionSelection& regions, float times)
 {
@@ -4456,6 +4240,9 @@ Editor::duplicate_some_regions (RegionSelection& regions, float times)
        RegionSelection sel = regions; // clear (below) may  clear the argument list if its the current region selection
        RegionSelection foo;
 
+       nframes_t const start_frame = regions.start ();
+       nframes_t const end_frame = regions.end_frame ();
+
        begin_reversible_command (_("duplicate region"));
 
        selection->clear_regions ();
@@ -4467,12 +4254,12 @@ Editor::duplicate_some_regions (RegionSelection& regions, float times)
                TimeAxisView& tv = (*i)->get_time_axis_view();
                RouteTimeAxisView* rtv = dynamic_cast<RouteTimeAxisView*> (&tv);
                latest_regionviews.clear ();
-               sigc::connection c = rtv->view()->RegionViewAdded.connect (mem_fun(*this, &Editor::collect_new_region_view));
+               sigc::connection c = rtv->view()->RegionViewAdded.connect (sigc::mem_fun(*this, &Editor::collect_new_region_view));
 
                playlist = (*i)->region()->playlist();
-                XMLNode &before = playlist->get_state();
-               playlist->duplicate (r, r->last_frame(), times);
-               session->add_command(new MementoCommand<Playlist>(*playlist, &before, &playlist->get_state()));
+                playlist->clear_history ();
+               playlist->duplicate (r, end_frame + (r->first_frame() - start_frame) + 1, times);
+               _session->add_command(new StatefulDiffCommand (playlist));
 
                c.disconnect ();
 
@@ -4511,10 +4298,9 @@ Editor::duplicate_selection (float times)
                if ((playlist = (*i)->playlist()) == 0) {
                        continue;
                }
-               XMLNode &before = playlist->get_state();
+                playlist->clear_history ();
                playlist->duplicate (*ri, selection->time[clicked_selection].end, times);
-               XMLNode &after = playlist->get_state();
-               session->add_command (new MementoCommand<Playlist>(*playlist, &before, &after));
+               _session->add_command (new StatefulDiffCommand (playlist));
 
                ++ri;
                if (ri == new_regions.end()) {
@@ -4532,7 +4318,7 @@ Editor::reset_point_selection ()
 
        for (PointSelection::iterator i = selection->points.begin(); i != selection->points.end(); ++i) {
 
-               AutomationTimeAxisView* atv = dynamic_cast<AutomationTimeAxisView*>(&(*i).track);
+               AutomationTimeAxisView* atv = dynamic_cast<AutomationTimeAxisView*>((*i).track);
 
                if (atv) {
                        atv->reset_objects (selection->points);
@@ -4558,10 +4344,9 @@ void
 Editor::clear_playlist (boost::shared_ptr<Playlist> playlist)
 {
        begin_reversible_command (_("clear playlist"));
-        XMLNode &before = playlist->get_state();
+        playlist->clear_history ();
        playlist->clear ();
-        XMLNode &after = playlist->get_state();
-       session->add_command (new MementoCommand<Playlist>(*playlist.get(), &before, &after));
+       _session->add_command (new StatefulDiffCommand (playlist));
        commit_reversible_command ();
 }
 
@@ -4595,10 +4380,20 @@ Editor::nudge_track (bool use_edit, bool forwards)
                        continue;
                }
 
-                XMLNode &before = playlist->get_state();
+                playlist->clear_history ();
+                playlist->clear_owned_history ();
+
                playlist->nudge_after (start, distance, forwards);
-                XMLNode &after = playlist->get_state();
-               session->add_command (new MementoCommand<Playlist>(*playlist, &before, &after));
+                
+                vector<StatefulDiffCommand*> cmds;
+
+                playlist->rdiff (cmds);
+
+                for (vector<StatefulDiffCommand*>::iterator c = cmds.begin(); c != cmds.end(); ++c) {
+                        _session->add_command (*c);
+                }
+
+                _session->add_command (new StatefulDiffCommand (playlist));
        }
 
        commit_reversible_command ();
@@ -4610,7 +4405,7 @@ Editor::remove_last_capture ()
        vector<string> choices;
        string prompt;
 
-       if (!session) {
+       if (!_session) {
                return;
        }
 
@@ -4621,21 +4416,21 @@ Editor::remove_last_capture ()
                choices.push_back (_("No, do nothing."));
                choices.push_back (_("Yes, destroy it."));
 
-               Gtkmm2ext::Choice prompter (prompt, choices);
+               Gtkmm2ext::Choice prompter (_("Destroy last capture"), prompt, choices);
 
                if (prompter.run () == 1) {
-                       session->remove_last_capture ();
+                       _session->remove_last_capture ();
                }
 
        } else {
-               session->remove_last_capture();
+               _session->remove_last_capture();
        }
 }
 
 void
 Editor::normalize_region ()
 {
-       if (!session) {
+       if (!_session) {
                return;
        }
 
@@ -4674,9 +4469,10 @@ Editor::normalize_region ()
                AudioRegionView* const arv = dynamic_cast<AudioRegionView*>(*r);
                if (!arv)
                        continue;
-               XMLNode &before = arv->region()->get_state();
+                arv->region()->clear_history ();
                arv->audio_region()->normalize_to (spin.get_value());
-               session->add_command (new MementoCommand<Region>(*(arv->region().get()), &before, &arv->region()->get_state()));
+               _session->add_command (new StatefulDiffCommand (arv->region()));
+                                       
        }
 
        commit_reversible_command ();
@@ -4689,7 +4485,7 @@ Editor::normalize_region ()
 void
 Editor::reset_region_scale_amplitude ()
 {
-       if (!session) {
+       if (!_session) {
                return;
        }
 
@@ -4707,9 +4503,9 @@ Editor::reset_region_scale_amplitude ()
                AudioRegionView* const arv = dynamic_cast<AudioRegionView*>(*r);
                if (!arv)
                        continue;
-               XMLNode &before = arv->region()->get_state();
+                arv->region()->clear_history ();
                arv->audio_region()->set_scale_amplitude (1.0f);
-               session->add_command (new MementoCommand<Region>(*(arv->region().get()), &before, &arv->region()->get_state()));
+               _session->add_command (new StatefulDiffCommand (arv->region()));
        }
 
        commit_reversible_command ();
@@ -4718,7 +4514,7 @@ Editor::reset_region_scale_amplitude ()
 void
 Editor::adjust_region_scale_amplitude (bool up)
 {
-       if (!session) {
+       if (!_session) {
                return;
        }
 
@@ -4734,10 +4530,12 @@ Editor::adjust_region_scale_amplitude (bool up)
 
        for (RegionSelection::iterator r = rs.begin(); r != rs.end(); ++r) {
                AudioRegionView* const arv = dynamic_cast<AudioRegionView*>(*r);
-               if (!arv)
+               if (!arv) {
                        continue;
-               XMLNode &before = arv->region()->get_state();
+                }
 
+                arv->region()->clear_history ();
+                
                double fraction = gain_to_slider_position (arv->audio_region()->scale_amplitude ());
 
                if (up) {
@@ -4759,7 +4557,7 @@ Editor::adjust_region_scale_amplitude (bool up)
                }
 
                arv->audio_region()->set_scale_amplitude (fraction);
-               session->add_command (new MementoCommand<Region>(*(arv->region().get()), &before, &arv->region()->get_state()));
+               _session->add_command (new StatefulDiffCommand (arv->region()));
        }
 
        commit_reversible_command ();
@@ -4769,18 +4567,18 @@ Editor::adjust_region_scale_amplitude (bool up)
 void
 Editor::reverse_region ()
 {
-       if (!session) {
+       if (!_session) {
                return;
        }
 
-       Reverse rev (*session);
+       Reverse rev (*_session);
        apply_filter (rev, _("reverse regions"));
 }
 
 void
 Editor::strip_region_silence ()
 {
-       if (!session) {
+       if (!_session) {
                return;
        }
 
@@ -4800,11 +4598,11 @@ Editor::strip_region_silence ()
                }
        }
 
-       StripSilenceDialog d (ar);
+       StripSilenceDialog d (_session, ar);
        int const r = d.run ();
 
        if (r == Gtk::RESPONSE_OK) {
-               StripSilence s (*session, d.threshold (), d.minimum_length (), d.fade_length ());
+               StripSilence s (*_session, d.threshold (), d.minimum_length (), d.fade_length ());
                apply_filter (s, _("strip silence"));
        }
 }
@@ -4845,7 +4643,7 @@ Editor::apply_midi_note_edit_op (MidiOperator& op)
                        cmd = apply_midi_note_edit_op_to_region (op, *mrv);
                        if (cmd) {
                                (*cmd)();
-                               session->add_command (cmd);
+                               _session->add_command (cmd);
                        }
                }
 
@@ -4859,22 +4657,24 @@ Editor::apply_midi_note_edit_op (MidiOperator& op)
 void
 Editor::quantize_region ()
 {
-       if (!session) {
+       if (!_session) {
                return;
        }
 
        QuantizeDialog* qd = new QuantizeDialog (*this);
 
        qd->present ();
-       qd->run ();
+       const int r = qd->run ();
        qd->hide ();
 
-       Quantize quant (*session, Plain,
-                       qd->snap_start(), qd->snap_end(),
-                       qd->start_grid_size(), qd->end_grid_size(),
-                       qd->strength(), qd->swing(), qd->threshold());
+       if (r == Gtk::RESPONSE_OK) {
+               Quantize quant (*_session, Plain,
+                               qd->snap_start(), qd->snap_end(),
+                               qd->start_grid_size(), qd->end_grid_size(),
+                               qd->strength(), qd->swing(), qd->threshold());
 
-       apply_midi_note_edit_op (quant);
+               apply_midi_note_edit_op (quant);
+       }
 }
 
 void
@@ -4903,8 +4703,8 @@ Editor::apply_filter (Filter& filter, string command)
 
                        if (arv->audio_region()->apply (filter) == 0) {
 
-                               XMLNode &before = playlist->get_state();
-
+                               playlist->clear_history ();
+                                
                                if (filter.results.empty ()) {
 
                                        /* no regions returned; remove the old one */
@@ -4926,8 +4726,7 @@ Editor::apply_filter (Filter& filter, string command)
 
                                }
 
-                               XMLNode &after = playlist->get_state();
-                               session->add_command(new MementoCommand<Playlist>(*playlist, &before, &after));
+                               _session->add_command(new StatefulDiffCommand (playlist));
                        } else {
                                goto out;
                        }
@@ -4999,13 +4798,13 @@ Editor::brush (nframes64_t pos)
 void
 Editor::reset_region_gain_envelopes ()
 {
-       RegionSelection rs = get_equivalent_regions (selection->regions, RouteGroup::Edit);
+       RegionSelection rs = get_equivalent_regions (selection->regions, ARDOUR::Properties::edit.property_id);
 
-       if (!session || rs.empty()) {
+       if (!_session || rs.empty()) {
                return;
        }
 
-       session->begin_reversible_command (_("reset region gain"));
+       _session->begin_reversible_command (_("reset region gain"));
 
        for (RegionSelection::iterator i = rs.begin(); i != rs.end(); ++i) {
                AudioRegionView* const arv = dynamic_cast<AudioRegionView*>(*i);
@@ -5014,144 +4813,138 @@ Editor::reset_region_gain_envelopes ()
                        XMLNode& before (alist->get_state());
 
                        arv->audio_region()->set_default_envelope ();
-                       session->add_command (new MementoCommand<AutomationList>(*arv->audio_region()->envelope().get(), &before, &alist->get_state()));
+                       _session->add_command (new MementoCommand<AutomationList>(*arv->audio_region()->envelope().get(), &before, &alist->get_state()));
                }
        }
 
-       session->commit_reversible_command ();
+       _session->commit_reversible_command ();
 }
 
 void
 Editor::toggle_gain_envelope_visibility ()
 {
-       RegionSelection rs = get_equivalent_regions (selection->regions, RouteGroup::Edit);
+       RegionSelection rs = get_equivalent_regions (selection->regions, ARDOUR::Properties::edit.property_id);
 
-       if (!session || rs.empty()) {
+       if (!_session || rs.empty()) {
                return;
        }
 
-       session->begin_reversible_command (_("region gain envelope visible"));
+       _session->begin_reversible_command (_("region gain envelope visible"));
 
        for (RegionSelection::iterator i = rs.begin(); i != rs.end(); ++i) {
                AudioRegionView* const arv = dynamic_cast<AudioRegionView*>(*i);
                if (arv) {
-                       XMLNode &before = arv->region()->get_state ();
+                        arv->region()->clear_history ();
                        arv->set_envelope_visible (!arv->envelope_visible());
-                       XMLNode &after = arv->region()->get_state ();
-                       session->add_command (new MementoCommand<Region> (*(arv->region().get()), &before, &after));
+                       _session->add_command (new StatefulDiffCommand (arv->region()));
                }
        }
 
-       session->commit_reversible_command ();
+       _session->commit_reversible_command ();
 }
 
 void
 Editor::toggle_gain_envelope_active ()
 {
-       RegionSelection rs = get_equivalent_regions (selection->regions, RouteGroup::Edit);
+       RegionSelection rs = get_equivalent_regions (selection->regions, ARDOUR::Properties::edit.property_id);
 
-       if (!session || rs.empty()) {
+       if (!_session || rs.empty()) {
                return;
        }
 
-       session->begin_reversible_command (_("region gain envelope active"));
+       _session->begin_reversible_command (_("region gain envelope active"));
 
        for (RegionSelection::iterator i = rs.begin(); i != rs.end(); ++i) {
                AudioRegionView* const arv = dynamic_cast<AudioRegionView*>(*i);
                if (arv) {
-                       XMLNode &before = arv->region()->get_state ();
+                       arv->region()->clear_history ();
                        arv->audio_region()->set_envelope_active (!arv->audio_region()->envelope_active());
-                       XMLNode &after = arv->region()->get_state ();
-                       session->add_command (new MementoCommand<Region> (*(arv->region().get()), &before, &after));
+                       _session->add_command (new StatefulDiffCommand (arv->region()));
                }
        }
 
-       session->commit_reversible_command ();
+       _session->commit_reversible_command ();
 }
 
 void
 Editor::toggle_region_lock ()
 {
-       RegionSelection rs = get_equivalent_regions (selection->regions, RouteGroup::Edit);
+       RegionSelection rs = get_equivalent_regions (selection->regions, ARDOUR::Properties::edit.property_id);
 
-       if (!session || rs.empty()) {
+       if (!_session || rs.empty()) {
                return;
        }
 
-       session->begin_reversible_command (_("region lock"));
+       _session->begin_reversible_command (_("region lock"));
 
        for (RegionSelection::iterator i = rs.begin(); i != rs.end(); ++i) {
-               XMLNode &before = (*i)->region()->get_state ();
+               (*i)->region()->clear_history ();
                (*i)->region()->set_locked (!(*i)->region()->locked());
-               XMLNode &after = (*i)->region()->get_state ();
-               session->add_command (new MementoCommand<Region> (*((*i)->region().get()), &before, &after));
+               _session->add_command (new StatefulDiffCommand ((*i)->region()));
        }
 
-       session->commit_reversible_command ();
+       _session->commit_reversible_command ();
 }
 
 void
 Editor::set_region_lock_style (Region::PositionLockStyle ps)
 {
-       RegionSelection rs = get_equivalent_regions (selection->regions, RouteGroup::Edit);
+       RegionSelection rs = get_equivalent_regions (selection->regions, ARDOUR::Properties::edit.property_id);
 
-       if (!session || rs.empty()) {
+       if (!_session || rs.empty()) {
                return;
        }
 
-       session->begin_reversible_command (_("region lock style"));
+       _session->begin_reversible_command (_("region lock style"));
 
        for (RegionSelection::iterator i = rs.begin(); i != rs.end(); ++i) {
-               XMLNode &before = (*i)->region()->get_state ();
+                (*i)->region()->clear_history ();
                (*i)->region()->set_position_lock_style (ps);
-               XMLNode &after = (*i)->region()->get_state ();
-               session->add_command (new MementoCommand<Region> (*((*i)->region().get()), &before, &after));
+               _session->add_command (new StatefulDiffCommand ((*i)->region()));
        }
 
-       session->commit_reversible_command ();
+       _session->commit_reversible_command ();
 }
 
 
 void
 Editor::toggle_region_mute ()
 {
-       RegionSelection rs = get_equivalent_regions (selection->regions, RouteGroup::Edit);
+       RegionSelection rs = get_equivalent_regions (selection->regions, ARDOUR::Properties::edit.property_id);
 
-       if (!session || rs.empty()) {
+       if (!_session || rs.empty()) {
                return;
        }
 
-       session->begin_reversible_command (_("region mute"));
+       _session->begin_reversible_command (_("region mute"));
 
        for (RegionSelection::iterator i = rs.begin(); i != rs.end(); ++i) {
-               XMLNode &before = (*i)->region()->get_state ();
+               (*i)->region()->clear_history ();
                (*i)->region()->set_muted (!(*i)->region()->muted());
-               XMLNode &after = (*i)->region()->get_state ();
-               session->add_command (new MementoCommand<Region> (*((*i)->region().get()), &before, &after));
+               _session->add_command (new StatefulDiffCommand ((*i)->region()));
        }
 
-       session->commit_reversible_command ();
+       _session->commit_reversible_command ();
 }
 
 void
 Editor::toggle_region_opaque ()
 {
-       RegionSelection rs = get_equivalent_regions (selection->regions, RouteGroup::Edit);
+       RegionSelection rs = get_equivalent_regions (selection->regions, ARDOUR::Properties::edit.property_id);
 
-       if (!session || rs.empty()) {
+       if (!_session || rs.empty()) {
                return;
        }
 
-       session->begin_reversible_command (_("region opacity"));
+       _session->begin_reversible_command (_("region opacity"));
 
        for (RegionSelection::iterator i = rs.begin(); i != rs.end(); ++i) {
-               XMLNode &before = (*i)->region()->get_state ();
+               (*i)->region()->clear_history ();
                (*i)->region()->set_opaque (!(*i)->region()->opaque());
-               XMLNode &after = (*i)->region()->get_state ();
-               session->add_command (new MementoCommand<Region> (*((*i)->region().get()), &before, &after));
+               _session->add_command (new StatefulDiffCommand ((*i)->region()));
        }
 
-       session->commit_reversible_command ();
+       _session->commit_reversible_command ();
 }
 
 void
@@ -5243,7 +5036,7 @@ Editor::set_fade_length (bool in)
                }
 
                XMLNode &after = alist->get_state();
-               session->add_command(new MementoCommand<AutomationList>(*alist, &before, &after));
+               _session->add_command(new MementoCommand<AutomationList>(*alist, &before, &after));
        }
 
        commit_reversible_command ();
@@ -5286,14 +5079,15 @@ Editor::toggle_fade_active (bool in)
                        have_switch = true;
                }
 
-               XMLNode &before = region->get_state();
+               region->clear_history ();
+
                if (in) {
                        region->set_fade_in_active (!yn);
                } else {
                        region->set_fade_out_active (!yn);
                }
-               XMLNode &after = region->get_state();
-               session->add_command(new MementoCommand<AudioRegion>(*region.get(), &before, &after));
+               
+               _session->add_command(new StatefulDiffCommand (region));
        }
 
        commit_reversible_command ();
@@ -5325,7 +5119,7 @@ Editor::set_fade_in_shape (AudioRegion::FadeShape shape)
                tmp->audio_region()->set_fade_in_shape (shape);
 
                XMLNode &after = alist->get_state();
-               session->add_command(new MementoCommand<AutomationList>(*alist.get(), &before, &after));
+               _session->add_command(new MementoCommand<AutomationList>(*alist.get(), &before, &after));
        }
 
        commit_reversible_command ();
@@ -5358,7 +5152,7 @@ Editor::set_fade_out_shape (AudioRegion::FadeShape shape)
                tmp->audio_region()->set_fade_out_shape (shape);
 
                XMLNode &after = alist->get_state();
-               session->add_command(new MementoCommand<AutomationList>(*alist.get(), &before, &after));
+               _session->add_command(new MementoCommand<AutomationList>(*alist.get(), &before, &after));
        }
 
        commit_reversible_command ();
@@ -5386,13 +5180,10 @@ Editor::set_fade_in_active (bool yn)
 
 
                boost::shared_ptr<AudioRegion> ar (tmp->audio_region());
-
-               XMLNode &before = ar->get_state();
-
+               
+                ar->clear_history ();
                ar->set_fade_in_active (yn);
-
-               XMLNode &after = ar->get_state();
-               session->add_command(new MementoCommand<AudioRegion>(*ar, &before, &after));
+               _session->add_command (new StatefulDiffCommand (ar));
        }
 
        commit_reversible_command ();
@@ -5420,12 +5211,9 @@ Editor::set_fade_out_active (bool yn)
 
                boost::shared_ptr<AudioRegion> ar (tmp->audio_region());
 
-               XMLNode &before = ar->get_state();
-
+                ar->clear_history ();
                ar->set_fade_out_active (yn);
-
-               XMLNode &after = ar->get_state();
-               session->add_command(new MementoCommand<AudioRegion>(*ar, &before, &after));
+               _session->add_command(new StatefulDiffCommand (ar));
        }
 
        commit_reversible_command ();
@@ -5481,7 +5269,7 @@ Editor::toggle_selected_region_fades (int dir)
 void
 Editor::update_region_fade_visibility ()
 {
-       bool _fade_visibility = session->config.get_show_region_fades ();
+       bool _fade_visibility = _session->config.get_show_region_fades ();
 
        for (TrackViewList::iterator i = track_views.begin(); i != track_views.end(); ++i) {
                AudioTimeAxisView* v = dynamic_cast<AudioTimeAxisView*>(*i);
@@ -5499,7 +5287,7 @@ Editor::update_region_fade_visibility ()
 void
 Editor::update_xfade_visibility ()
 {
-       _xfade_visibility = session->config.get_xfades_visible ();
+       _xfade_visibility = _session->config.get_xfades_visible ();
 
        for (TrackViewList::iterator i = track_views.begin(); i != track_views.end(); ++i) {
                AudioTimeAxisView* v = dynamic_cast<AudioTimeAxisView*>(*i);
@@ -5544,7 +5332,7 @@ void
 Editor::set_playhead_cursor ()
 {
        if (entered_marker) {
-               session->request_locate (entered_marker->position(), session->transport_rolling());
+               _session->request_locate (entered_marker->position(), _session->transport_rolling());
        } else {
                nframes64_t where;
                bool ignored;
@@ -5555,8 +5343,8 @@ Editor::set_playhead_cursor ()
 
                snap_to (where);
 
-               if (session) {
-                       session->request_locate (where, session->transport_rolling());
+               if (_session) {
+                       _session->request_locate (where, _session->transport_rolling());
                }
        }
 }
@@ -5698,7 +5486,7 @@ Editor::ensure_track_visible(TimeAxisView *track)
 void
 Editor::set_loop_from_selection (bool play)
 {
-       if (session == 0 || selection->time.empty()) {
+       if (_session == 0 || selection->time.empty()) {
                return;
        }
 
@@ -5708,15 +5496,15 @@ Editor::set_loop_from_selection (bool play)
        set_loop_range (start, end,  _("set loop range from selection"));
 
        if (play) {
-               session->request_play_loop (true);
-               session->request_locate (start, true);
+               _session->request_play_loop (true);
+               _session->request_locate (start, true);
        }
 }
 
 void
 Editor::set_loop_from_edit_range (bool play)
 {
-       if (session == 0) {
+       if (_session == 0) {
                return;
        }
 
@@ -5730,8 +5518,8 @@ Editor::set_loop_from_edit_range (bool play)
        set_loop_range (start, end,  _("set loop range from edit range"));
 
        if (play) {
-               session->request_play_loop (true);
-               session->request_locate (start, true);
+               _session->request_play_loop (true);
+               _session->request_locate (start, true);
        }
 }
 
@@ -5761,15 +5549,15 @@ Editor::set_loop_from_region (bool play)
        set_loop_range (start, end, _("set loop range from region"));
 
        if (play) {
-               session->request_play_loop (true);
-               session->request_locate (start, true);
+               _session->request_play_loop (true);
+               _session->request_locate (start, true);
        }
 }
 
 void
 Editor::set_punch_from_selection ()
 {
-       if (session == 0 || selection->time.empty()) {
+       if (_session == 0 || selection->time.empty()) {
                return;
        }
 
@@ -5782,7 +5570,7 @@ Editor::set_punch_from_selection ()
 void
 Editor::set_punch_from_edit_range ()
 {
-       if (session == 0) {
+       if (_session == 0) {
                return;
        }
 
@@ -5839,7 +5627,7 @@ Editor::pitch_shift_regions ()
 void
 Editor::use_region_as_bar ()
 {
-       if (!session) {
+       if (!_session) {
                return;
        }
 
@@ -5870,7 +5658,7 @@ Editor::define_one_bar (nframes64_t start, nframes64_t end)
 {
        nframes64_t length = end - start;
 
-       const Meter& m (session->tempo_map().meter_at (start));
+       const Meter& m (_session->tempo_map().meter_at (start));
 
        /* length = 1 bar */
 
@@ -5882,7 +5670,7 @@ Editor::define_one_bar (nframes64_t start, nframes64_t end)
 
        /* beats per minute = */
 
-       double beats_per_minute = (session->frame_rate() * 60.0) / frames_per_beat;
+       double beats_per_minute = (_session->frame_rate() * 60.0) / frames_per_beat;
 
        /* now decide whether to:
 
@@ -5891,11 +5679,11 @@ Editor::define_one_bar (nframes64_t start, nframes64_t end)
 
        */
 
-       const TempoSection& t (session->tempo_map().tempo_section_at (start));
+       const TempoSection& t (_session->tempo_map().tempo_section_at (start));
 
        bool do_global = false;
 
-       if ((session->tempo_map().n_tempos() == 1) && (session->tempo_map().n_meters() == 1)) {
+       if ((_session->tempo_map().n_tempos() == 1) && (_session->tempo_map().n_meters() == 1)) {
 
                /* only 1 tempo & 1 meter: ask if the user wants to set the tempo
                   at the start, or create a new marker
@@ -5905,8 +5693,13 @@ Editor::define_one_bar (nframes64_t start, nframes64_t end)
                options.push_back (_("Cancel"));
                options.push_back (_("Add new marker"));
                options.push_back (_("Set global tempo"));
-               Choice c (_("Do you want to set the global tempo or add new tempo marker?"),
-                         options);
+
+               Choice c (
+                       _("Define one bar"),
+                       _("Do you want to set the global tempo or add a new tempo marker?"),
+                       options
+                       );
+               
                c.set_default_response (2);
 
                switch (c.run()) {
@@ -5930,19 +5723,19 @@ Editor::define_one_bar (nframes64_t start, nframes64_t end)
        }
 
        begin_reversible_command (_("set tempo from region"));
-       XMLNode& before (session->tempo_map().get_state());
+       XMLNode& before (_session->tempo_map().get_state());
 
        if (do_global) {
-               session->tempo_map().change_initial_tempo (beats_per_minute, t.note_type());
+               _session->tempo_map().change_initial_tempo (beats_per_minute, t.note_type());
        } else if (t.frame() == start) {
-               session->tempo_map().change_existing_tempo_at (start, beats_per_minute, t.note_type());
+               _session->tempo_map().change_existing_tempo_at (start, beats_per_minute, t.note_type());
        } else {
-               session->tempo_map().add_tempo (Tempo (beats_per_minute, t.note_type()), start);
+               _session->tempo_map().add_tempo (Tempo (beats_per_minute, t.note_type()), start);
        }
 
-       XMLNode& after (session->tempo_map().get_state());
+       XMLNode& after (_session->tempo_map().get_state());
 
-       session->add_command (new MementoCommand<TempoMap>(session->tempo_map(), &before, &after));
+       _session->add_command (new MementoCommand<TempoMap>(_session->tempo_map(), &before, &after));
        commit_reversible_command ();
 }
 
@@ -5951,7 +5744,7 @@ Editor::split_region_at_transients ()
 {
        AnalysisFeatureList positions;
 
-       if (!session) {
+       if (!_session) {
                return;
        }
 
@@ -5963,7 +5756,7 @@ Editor::split_region_at_transients ()
                return;
        }
 
-       session->begin_reversible_command (_("split regions"));
+       _session->begin_reversible_command (_("split regions"));
 
        for (RegionSelection::iterator i = rs.begin(); i != rs.end(); ) {
 
@@ -5982,7 +5775,7 @@ Editor::split_region_at_transients ()
                i = tmp;
        }
 
-       session->commit_reversible_command ();
+       _session->commit_reversible_command ();
 
 }
 
@@ -6041,7 +5834,7 @@ Editor::split_region_at_points (boost::shared_ptr<Region> r, AnalysisFeatureList
 
        nframes64_t pos = r->position();
 
-       XMLNode& before (pl->get_state());
+        pl->clear_history ();
 
        x = positions.begin();
 
@@ -6081,13 +5874,20 @@ Editor::split_region_at_points (boost::shared_ptr<Region> r, AnalysisFeatureList
 
                string new_name;
 
-               if (session->region_name (new_name, r->name())) {
+               if (RegionFactory::region_name (new_name, r->name())) {
                        break;
                }
 
                /* do NOT announce new regions 1 by one, just wait till they are all done */
 
-               boost::shared_ptr<Region> nr = RegionFactory::create (r->sources(), file_start, len, new_name, 0, Region::DefaultFlags, false);
+               PropertyList plist; 
+               
+               plist.add (ARDOUR::Properties::start, file_start);
+               plist.add (ARDOUR::Properties::length, len);
+               plist.add (ARDOUR::Properties::name, new_name);
+               plist.add (ARDOUR::Properties::layer, 0);
+
+               boost::shared_ptr<Region> nr = RegionFactory::create (r->sources(), plist, false);
                pl->add_region (nr, pos);
 
                pos += len;
@@ -6100,7 +5900,14 @@ Editor::split_region_at_points (boost::shared_ptr<Region> r, AnalysisFeatureList
                        file_start = r->start() + (pos - r->position());
                        len = r->last_frame() - pos;
 
-                       nr = RegionFactory::create (r->sources(), file_start, len, new_name, 0, Region::DefaultFlags);
+                       PropertyList plist2; 
+                       
+                       plist2.add (ARDOUR::Properties::start, file_start);
+                       plist2.add (ARDOUR::Properties::length, len);
+                       plist2.add (ARDOUR::Properties::name, new_name);
+                       plist2.add (ARDOUR::Properties::layer, 0);
+
+                       nr = RegionFactory::create (r->sources(), plist2); 
                        pl->add_region (nr, pos);
 
                        break;
@@ -6109,9 +5916,7 @@ Editor::split_region_at_points (boost::shared_ptr<Region> r, AnalysisFeatureList
 
        pl->thaw ();
 
-       XMLNode& after (pl->get_state());
-
-       session->add_command (new MementoCommand<Playlist>(*pl, &before, &after));
+       _session->add_command (new StatefulDiffCommand (pl));
 }
 
 void
@@ -6119,11 +5924,11 @@ Editor::tab_to_transient (bool forward)
 {
        AnalysisFeatureList positions;
 
-       if (!session) {
+       if (!_session) {
                return;
        }
 
-       nframes64_t pos = session->audible_frame ();
+       nframes64_t pos = _session->audible_frame ();
 
        if (!selection->tracks.empty()) {
 
@@ -6132,9 +5937,9 @@ Editor::tab_to_transient (bool forward)
                        RouteTimeAxisView* rtv = dynamic_cast<RouteTimeAxisView*> (*t);
 
                        if (rtv) {
-                               boost::shared_ptr<Diskstream> ds = rtv->get_diskstream();
-                               if (ds) {
-                                       boost::shared_ptr<Playlist> pl = rtv->get_diskstream()->playlist ();
+                               boost::shared_ptr<Track> tr = rtv->track();
+                               if (tr) {
+                                       boost::shared_ptr<Playlist> pl = tr->playlist ();
                                        if (pl) {
                                                nframes64_t result = pl->find_next_transient (pos, forward ? 1 : -1);
 
@@ -6161,7 +5966,7 @@ Editor::tab_to_transient (bool forward)
                }
        }
 
-       TransientDetector::cleanup_transients (positions, session->frame_rate(), 3.0);
+       TransientDetector::cleanup_transients (positions, _session->frame_rate(), 3.0);
 
        if (forward) {
                AnalysisFeatureList::iterator x;
@@ -6173,7 +5978,7 @@ Editor::tab_to_transient (bool forward)
                }
 
                if (x != positions.end ()) {
-                       session->request_locate (*x);
+                       _session->request_locate (*x);
                }
 
        } else {
@@ -6186,19 +5991,19 @@ Editor::tab_to_transient (bool forward)
                }
 
                if (x != positions.rend ()) {
-                       session->request_locate (*x);
+                       _session->request_locate (*x);
                }
        }
 }
 void
 Editor::playhead_forward_to_grid ()
 {
-       if (!session) return;
+       if (!_session) return;
        nframes64_t pos = playhead_cursor->current_frame;
        if (pos < max_frames - 1) {
                pos += 2;
                snap_to_internal (pos, 1, false);
-               session->request_locate (pos);
+               _session->request_locate (pos);
        }
 }
 
@@ -6206,12 +6011,12 @@ Editor::playhead_forward_to_grid ()
 void
 Editor::playhead_backward_to_grid ()
 {
-       if (!session) return;
+       if (!_session) return;
        nframes64_t pos = playhead_cursor->current_frame;
        if (pos > 2) {
                pos -= 2;
                snap_to_internal (pos, -1, false);
-               session->request_locate (pos);
+               _session->request_locate (pos);
        }
 }
 
@@ -6318,14 +6123,21 @@ Editor::remove_tracks ()
                choices.push_back (_("Yes, remove it."));
        }
 
-       Choice prompter (prompt, choices);
+       string title;
+       if (ntracks) {
+               title = string_compose (_("Remove %1"), trackstr);
+       } else {
+               title = string_compose (_("Remove %1"), busstr);
+       }
+
+       Choice prompter (title, prompt, choices);
 
        if (prompter.run () != 1) {
                return;
        }
 
        for (vector<boost::shared_ptr<Route> >::iterator x = routes.begin(); x != routes.end(); ++x) {
-               session->remove_route (*x);
+               _session->remove_route (*x);
        }
 }
 
@@ -6349,9 +6161,9 @@ Editor::do_insert_time ()
        Label time_label (_("Time to insert:"));
        time_label.set_alignment (1, 0.5);
        table.attach (time_label, 0, 1, 0, 1, FILL | EXPAND);
-       AudioClock clock ("insertTimeClock", true, X_("InsertTimeClock"), true, true, true);
+       AudioClock clock ("insertTimeClock", true, X_("InsertTimeClock"), true, false, true, true);
        clock.set (0);
-       clock.set_session (session);
+       clock.set_session (_session);
        clock.set_bbt_reference (pos);
        table.attach (clock, 1, 2, 0, 1);
 
@@ -6425,7 +6237,8 @@ Editor::insert_time (nframes64_t pos, nframes64_t frames, InsertTimeOption opt,
 
                if (pl) {
 
-                       XMLNode &before = pl->get_state();
+                       pl->clear_history ();
+                        pl->clear_owned_history ();
 
                        if (opt == SplitIntersected) {
                                pl->split (pos);
@@ -6433,9 +6246,17 @@ Editor::insert_time (nframes64_t pos, nframes64_t frames, InsertTimeOption opt,
 
                        pl->shift (pos, frames, (opt == MoveIntersected), ignore_music_glue);
 
-                       XMLNode &after = pl->get_state();
-
-                       session->add_command (new MementoCommand<Playlist> (*pl, &before, &after));
+                        vector<StatefulDiffCommand*> cmds;
+                        
+                        pl->rdiff (cmds);
+                        
+                        cerr << "Shift generated " << cmds.size() << " sdc's\n";
+
+                        for (vector<StatefulDiffCommand*>::iterator c = cmds.begin(); c != cmds.end(); ++c) {
+                                _session->add_command (*c);
+                        }
+                        
+                       _session->add_command (new StatefulDiffCommand (pl));
                        commit = true;
                }
 
@@ -6450,8 +6271,8 @@ Editor::insert_time (nframes64_t pos, nframes64_t frames, InsertTimeOption opt,
        /* markers */
        if (markers_too) {
                bool moved = false;
-               XMLNode& before (session->locations()->get_state());
-               Locations::LocationList copy (session->locations()->list());
+               XMLNode& before (_session->locations()->get_state());
+               Locations::LocationList copy (_session->locations()->list());
 
                for (Locations::LocationList::iterator i = copy.begin(); i != copy.end(); ++i) {
 
@@ -6467,13 +6288,13 @@ Editor::insert_time (nframes64_t pos, nframes64_t frames, InsertTimeOption opt,
                }
 
                if (moved) {
-                       XMLNode& after (session->locations()->get_state());
-                       session->add_command (new MementoCommand<Locations>(*session->locations(), &before, &after));
+                       XMLNode& after (_session->locations()->get_state());
+                       _session->add_command (new MementoCommand<Locations>(*_session->locations(), &before, &after));
                }
        }
 
        if (tempo_too) {
-               session->tempo_map().insert_time (pos, frames);
+               _session->tempo_map().insert_time (pos, frames);
        }
 
        if (commit) {
@@ -6488,7 +6309,7 @@ Editor::fit_selected_tracks ()
 }
 
 void
-Editor::fit_tracks (TrackSelection & tracks)
+Editor::fit_tracks (TrackViewList & tracks)
 {
        if (tracks.empty()) {
                return;
@@ -6590,7 +6411,7 @@ void
 Editor::start_visual_state_op (uint32_t n)
 {
        if (visual_state_op_connection.empty()) {
-               visual_state_op_connection = Glib::signal_timeout().connect (bind (mem_fun (*this, &Editor::end_visual_state_op), n), 1000);
+               visual_state_op_connection = Glib::signal_timeout().connect (sigc::bind (sigc::mem_fun (*this, &Editor::end_visual_state_op), n), 1000);
        }
 }