No-op: rename a few variables and add/fix some comments.
[ardour.git] / libs / ardour / playlist.cc
index 5660e52a52b3cc6ada352d00fe06976781dd6a6f..c71d53deca6dc009d6ac769b66be5ed695847b64 100644 (file)
@@ -1,5 +1,5 @@
 /*
-    Copyright (C) 2000-2003 Paul Davis 
+    Copyright (C) 2000-2003 Paul Davis
 
     This program is free software; you can redistribute it and/or modify
     it under the terms of the GNU General Public License as published by
 #include <string>
 #include <climits>
 
-#include <sigc++/bind.h>
+#include <boost/lexical_cast.hpp>
 
 #include "pbd/failed_constructor.h"
-#include "pbd/stl_delete.h"
+#include "pbd/stateful_diff_command.h"
 #include "pbd/xml++.h"
-#include "pbd/stacktrace.h"
 
+#include "ardour/debug.h"
 #include "ardour/playlist.h"
 #include "ardour/session.h"
 #include "ardour/region.h"
 #include "ardour/region_factory.h"
 #include "ardour/playlist_factory.h"
 #include "ardour/transient_detector.h"
+#include "ardour/session_playlists.h"
 
 #include "i18n.h"
 
@@ -45,10 +46,16 @@ using namespace std;
 using namespace ARDOUR;
 using namespace PBD;
 
+namespace ARDOUR {
+namespace Properties {
+PBD::PropertyDescriptor<bool> regions;
+}
+}
+
 struct ShowMeTheList {
     ShowMeTheList (boost::shared_ptr<Playlist> pl, const string& n) : playlist (pl), name (n) {}
-    ~ShowMeTheList () { 
-           cerr << ">>>>" << name << endl; playlist->dump(); cerr << "<<<<" << name << endl << endl; 
+    ~ShowMeTheList () {
+           cerr << ">>>>" << name << endl; playlist->dump(); cerr << "<<<<" << name << endl << endl;
     };
     boost::shared_ptr<Playlist> playlist;
     string name;
@@ -60,6 +67,23 @@ struct RegionSortByLayer {
     }
 };
 
+struct RegionSortByLayerWithPending {
+       bool operator () (boost::shared_ptr<Region> a, boost::shared_ptr<Region> b) {
+
+               double p = a->layer ();
+               if (a->pending_explicit_relayer()) {
+                       p += 0.5;
+               }
+
+               double q = b->layer ();
+               if (b->pending_explicit_relayer()) {
+                       q += 0.5;
+               }
+
+               return p < q;
+       }
+};
+
 struct RegionSortByPosition {
     bool operator() (boost::shared_ptr<Region> a, boost::shared_ptr<Region> b) {
            return a->position() < b->position();
@@ -72,38 +96,95 @@ struct RegionSortByLastLayerOp {
     }
 };
 
+void
+Playlist::make_property_quarks ()
+{
+        Properties::regions.property_id = g_quark_from_static_string (X_("regions"));
+        DEBUG_TRACE (DEBUG::Properties, string_compose ("quark for regions = %1\n",         Properties::regions.property_id));
+}
+
+RegionListProperty::RegionListProperty (Playlist& pl)
+        : SequenceProperty<std::list<boost::shared_ptr<Region> > > (Properties::regions.property_id, boost::bind (&Playlist::update, &pl, _1))
+        , _playlist (pl)
+{
+}
+
+boost::shared_ptr<Region>
+RegionListProperty::lookup_id (const ID& id)
+{
+        boost::shared_ptr<Region> ret =  _playlist.region_by_id (id);
+        
+        if (!ret) {
+                ret = RegionFactory::region_by_id (id);
+        }
+
+        return ret;
+}
+
+RegionListProperty*
+RegionListProperty::copy_for_history () const
+{
+        RegionListProperty* copy = new RegionListProperty (_playlist);
+        /* this is all we need */
+        copy->_change = _change;
+        return copy;
+}
+
+void 
+RegionListProperty::diff (PropertyList& undo, PropertyList& redo) const
+{
+        if (changed()) {
+               /* list of the removed/added regions since clear_history() was last called */
+                RegionListProperty* a = copy_for_history ();
+
+               /* the same list, but with removed/added lists swapped (for undo purposes) */
+                RegionListProperty* b = copy_for_history ();
+                b->invert_changes ();
+
+                undo.add (b);
+                redo.add (a);
+        }
+}
 
 Playlist::Playlist (Session& sess, string nom, DataType type, bool hide)
        : SessionObject(sess, nom)
+        , regions (*this)
        , _type(type)
 {
        init (hide);
        first_set_state = false;
        _name = nom;
-       
+        _set_sort_id ();
+
 }
 
 Playlist::Playlist (Session& sess, const XMLNode& node, DataType type, bool hide)
        : SessionObject(sess, "unnamed playlist")
-       , _type(type)
+        , regions (*this)      
+        , _type(type)
+
 {
        const XMLProperty* prop = node.property("type");
        assert(!prop || DataType(prop->value()) == _type);
 
        init (hide);
        _name = "unnamed"; /* reset by set_state */
+        _set_sort_id ();
 
        /* set state called by derived class */
 }
 
 Playlist::Playlist (boost::shared_ptr<const Playlist> other, string namestr, bool hide)
-       : SessionObject(other->_session, namestr), _type(other->_type), _orig_diskstream_id(other->_orig_diskstream_id)
+       : SessionObject(other->_session, namestr)
+        , regions (*this)
+       , _type(other->_type)
+       , _orig_diskstream_id(other->_orig_diskstream_id)
 {
        init (hide);
 
        RegionList tmp;
        other->copy_regions (tmp);
-       
+
        in_set_state++;
 
        for (list<boost::shared_ptr<Region> >::iterator x = tmp.begin(); x != tmp.end(); ++x) {
@@ -123,29 +204,32 @@ Playlist::Playlist (boost::shared_ptr<const Playlist> other, string namestr, boo
        subcnt = 0;
        _read_data_count = 0;
        _frozen = other->_frozen;
-       
+
        layer_op_counter = other->layer_op_counter;
        freeze_length = other->freeze_length;
 }
 
-Playlist::Playlist (boost::shared_ptr<const Playlist> other, nframes_t start, nframes_t cnt, string str, bool hide)
-       : SessionObject(other->_session, str), _type(other->_type), _orig_diskstream_id(other->_orig_diskstream_id)
+Playlist::Playlist (boost::shared_ptr<const Playlist> other, framepos_t start, framecnt_t cnt, string str, bool hide)
+       : SessionObject(other->_session, str)
+        , regions (*this)
+       , _type(other->_type)
+       , _orig_diskstream_id(other->_orig_diskstream_id)
 {
        RegionLock rlock2 (const_cast<Playlist*> (other.get()));
 
-       nframes_t end = start + cnt - 1;
+       framepos_t end = start + cnt - 1;
 
        init (hide);
 
        in_set_state++;
 
-       for (RegionList::const_iterator i = other->regions.begin(); i != other->regions.end(); i++) {
+       for (RegionList::const_iterator i = other->regions.begin(); i != other->regions.end(); ++i) {
 
                boost::shared_ptr<Region> region;
                boost::shared_ptr<Region> new_region;
-               nframes_t offset = 0;
-               nframes_t position = 0;
-               nframes_t len = 0;
+               frameoffset_t offset = 0;
+               framepos_t position = 0;
+               framecnt_t len = 0;
                string    new_name;
                OverlapType overlap;
 
@@ -182,13 +266,20 @@ Playlist::Playlist (boost::shared_ptr<const Playlist> other, nframes_t start, nf
                        break;
                }
 
-               _session.region_name (new_name, region->name(), false);
+               RegionFactory::region_name (new_name, region->name(), false);
+
+               PropertyList plist; 
 
-               new_region = RegionFactory::RegionFactory::create (region, offset, len, new_name, region->layer(), region->flags());
+               plist.add (Properties::start, region->start() + offset);
+               plist.add (Properties::length, len);
+               plist.add (Properties::name, new_name);
+               plist.add (Properties::layer, region->layer());
+
+               new_region = RegionFactory::RegionFactory::create (region, plist);
 
                add_region_internal (new_region, position);
        }
-       
+
        in_set_state--;
        first_set_state = false;
 
@@ -206,7 +297,7 @@ void
 Playlist::release ()
 {
        if (_refcnt > 0) {
-               _refcnt--; 
+               _refcnt--;
        }
 
        if (_refcnt == 0) {
@@ -227,10 +318,14 @@ Playlist::copy_regions (RegionList& newlist) const
 void
 Playlist::init (bool hide)
 {
+        add_property (regions);
+        _xml_node_name = X_("Playlist");
+
        g_atomic_int_set (&block_notifications, 0);
        g_atomic_int_set (&ignore_state_changes, 0);
-       pending_modified = false;
+       pending_contents_change = false;
        pending_length = false;
+       pending_layering = false;
        first_set_state = true;
        _refcnt = 0;
        _hidden = hide;
@@ -238,6 +333,7 @@ Playlist::init (bool hide)
        _shuffling = false;
        _nudging = false;
        in_set_state = 0;
+        in_update = false;
        _edit_mode = Config->get_edit_mode();
        in_flush = false;
        in_partition = false;
@@ -246,12 +342,18 @@ Playlist::init (bool hide)
        _frozen = false;
        layer_op_counter = 0;
        freeze_length = 0;
+       _explicit_relayering = false;
 
-       Modified.connect (mem_fun (*this, &Playlist::mark_session_dirty));
+       _session.history().BeginUndoRedo.connect_same_thread (*this, boost::bind (&Playlist::begin_undo, this));
+       _session.history().EndUndoRedo.connect_same_thread (*this, boost::bind (&Playlist::end_undo, this));
+       
+       ContentsChanged.connect_same_thread (*this, boost::bind (&Playlist::mark_session_dirty, this));
 }
 
 Playlist::~Playlist ()
 {
+       DEBUG_TRACE (DEBUG::Destruction, string_compose ("Playlist %1 destructor\n", _name));
+
        {
                RegionLock rl (this);
 
@@ -263,6 +365,32 @@ Playlist::~Playlist ()
        /* GoingAway must be emitted by derived classes */
 }
 
+void
+Playlist::_set_sort_id ()
+{
+        /*
+          Playlists are given names like <track name>.<id>
+          or <track name>.<edit group name>.<id> where id
+          is an integer. We extract the id and sort by that.
+        */
+        
+        size_t dot_position = _name.val().find_last_of(".");
+
+        if (dot_position == string::npos) {
+                _sort_id = 0;
+        } else {
+                string t = _name.val().substr(dot_position + 1);
+
+                try {
+                        _sort_id = boost::lexical_cast<int>(t);
+                }
+
+                catch (boost::bad_lexical_cast e) {
+                        _sort_id = 0;
+                }
+        }
+}
+
 bool
 Playlist::set_name (const string& str)
 {
@@ -274,19 +402,37 @@ Playlist::set_name (const string& str)
 
        if (_refcnt > 2) {
                return false;
-       } else {
-               return SessionObject::set_name(str);
-       }
+       } 
+
+        bool ret =  SessionObject::set_name(str);
+        if (ret) {
+                _set_sort_id ();
+        }
+        return ret;
 }
 
 /***********************************************************************
  CHANGE NOTIFICATION HANDLING
+
  Notifications must be delayed till the region_lock is released. This
  is necessary because handlers for the signals may need to acquire
  the lock (e.g. to read from the playlist).
  ***********************************************************************/
 
+void
+Playlist::begin_undo ()
+{
+        in_update = true;
+       freeze ();
+}
+
+void
+Playlist::end_undo ()
+{
+       thaw ();
+        in_update = false;
+}
+
 void
 Playlist::freeze ()
 {
@@ -312,19 +458,31 @@ Playlist::delay_notifications ()
 void
 Playlist::release_notifications ()
 {
-       if (g_atomic_int_dec_and_test (&block_notifications)) { 
+       if (g_atomic_int_dec_and_test (&block_notifications)) {
                flush_notifications ();
-       } 
+        }
+
+}
+
+void
+Playlist::notify_contents_changed ()
+{
+       if (holding_state ()) {
+               pending_contents_change = true;
+       } else {
+               pending_contents_change = false;
+               ContentsChanged(); /* EMIT SIGNAL */
+       }
 }
 
 void
-Playlist::notify_modified ()
+Playlist::notify_layering_changed ()
 {
        if (holding_state ()) {
-               pending_modified = true;
+               pending_layering = true;
        } else {
-               pending_modified = false;
-               Modified(); /* EMIT SIGNAL */
+               pending_layering = false;
+               LayeringChanged(); /* EMIT SIGNAL */
        }
 }
 
@@ -333,7 +491,7 @@ Playlist::notify_region_removed (boost::shared_ptr<Region> r)
 {
        if (holding_state ()) {
                pending_removes.insert (r);
-               pending_modified = true;
+               pending_contents_change = true;
                pending_length = true;
        } else {
                /* this might not be true, but we have to act
@@ -341,24 +499,24 @@ Playlist::notify_region_removed (boost::shared_ptr<Region> r)
                */
                pending_length = false;
                LengthChanged (); /* EMIT SIGNAL */
-               pending_modified = false;
+               pending_contents_change = false;
                RegionRemoved (boost::weak_ptr<Region> (r)); /* EMIT SIGNAL */
-               Modified (); /* EMIT SIGNAL */
+               ContentsChanged (); /* EMIT SIGNAL */
        }
 }
 
 void
 Playlist::notify_region_moved (boost::shared_ptr<Region> r)
 {
-       Evoral::RangeMove<nframes_t> const move (r->last_position (), r->length (), r->position ());
-                       
+       Evoral::RangeMove<framepos_t> const move (r->last_position (), r->length (), r->position ());
+
        if (holding_state ()) {
 
                pending_range_moves.push_back (move);
-               
+
        } else {
 
-               list< Evoral::RangeMove<nframes_t> > m;
+               list< Evoral::RangeMove<framepos_t> > m;
                m.push_back (move);
                RangesMoved (m);
        }
@@ -371,17 +529,17 @@ Playlist::notify_region_added (boost::shared_ptr<Region> r)
        /* the length change might not be true, but we have to act
           as though it could be.
        */
-
+        
        if (holding_state()) {
                pending_adds.insert (r);
-               pending_modified = true;
+               pending_contents_change = true;
                pending_length = true;
        } else {
                pending_length = false;
                LengthChanged (); /* EMIT SIGNAL */
-               pending_modified = false;
+               pending_contents_change = false;
                RegionAdded (boost::weak_ptr<Region> (r)); /* EMIT SIGNAL */
-               Modified (); /* EMIT SIGNAL */
+               ContentsChanged (); /* EMIT SIGNAL */
        }
 }
 
@@ -393,8 +551,8 @@ Playlist::notify_length_changed ()
        } else {
                pending_length = false;
                LengthChanged(); /* EMIT SIGNAL */
-               pending_modified = false;
-               Modified (); /* EMIT SIGNAL */
+               pending_contents_change = false;
+               ContentsChanged (); /* EMIT SIGNAL */
        }
 }
 
@@ -403,7 +561,9 @@ Playlist::flush_notifications ()
 {
        set<boost::shared_ptr<Region> > dependent_checks_needed;
        set<boost::shared_ptr<Region> >::iterator s;
-       uint32_t n = 0;
+       uint32_t regions_changed = false;
+       bool check_length = false;
+       framecnt_t old_length = 0;
 
        if (in_flush) {
                return;
@@ -411,9 +571,17 @@ Playlist::flush_notifications ()
 
        in_flush = true;
 
+       if (!pending_bounds.empty() || !pending_removes.empty() || !pending_adds.empty()) {
+               regions_changed = true;
+               if (!pending_length) {
+                       old_length = _get_maximum_extent ();
+                       check_length = true;
+               }
+       }
+
        /* we have no idea what order the regions ended up in pending
           bounds (it could be based on selection order, for example).
-          so, to preserve layering in the "most recently moved is higher" 
+          so, to preserve layering in the "most recently moved is higher"
           model, sort them by existing layer, then timestamp them.
        */
 
@@ -424,37 +592,42 @@ Playlist::flush_notifications ()
                if (_session.config.get_layer_model() == MoveAddHigher) {
                        timestamp_layer_op (*r);
                }
-
-               pending_length = true;
                dependent_checks_needed.insert (*r);
-
-               n++;
        }
 
        for (s = pending_removes.begin(); s != pending_removes.end(); ++s) {
                remove_dependents (*s);
+               // cerr << _name << " sends RegionRemoved\n";
                RegionRemoved (boost::weak_ptr<Region> (*s)); /* EMIT SIGNAL */
-               n++;
        }
 
        for (s = pending_adds.begin(); s != pending_adds.end(); ++s) {
+               // cerr << _name << " sends RegionAdded\n";
                RegionAdded (boost::weak_ptr<Region> (*s)); /* EMIT SIGNAL */
                dependent_checks_needed.insert (*s);
-               n++;
        }
 
-       if ((freeze_length != _get_maximum_extent()) || pending_length) {
-               pending_length = 0;
+       if (check_length) {
+               if (old_length != _get_maximum_extent()) {
+                       pending_length = true;
+                       // cerr << _name << " length has changed\n";
+               }
+       }
+
+       if (pending_length || (freeze_length != _get_maximum_extent())) {
+               pending_length = false;
+               // cerr << _name << " sends LengthChanged\n";
                LengthChanged(); /* EMIT SIGNAL */
-               n++;
        }
 
-       if (n || pending_modified) {
+       if (regions_changed || pending_contents_change) {
                if (!in_set_state) {
                        relayer ();
                }
-               pending_modified = false;
-               Modified (); /* EMIT SIGNAL */          
+               pending_contents_change = false;
+               // cerr << _name << " sends 5 contents change @ " << get_microseconds() << endl;
+               ContentsChanged (); /* EMIT SIGNAL */
+               // cerr << _name << "done contents change @ " << get_microseconds() << endl;
        }
 
        for (s = dependent_checks_needed.begin(); s != dependent_checks_needed.end(); ++s) {
@@ -462,15 +635,24 @@ Playlist::flush_notifications ()
        }
 
        if (!pending_range_moves.empty ()) {
+               // cerr << _name << " sends RangesMoved\n";
                RangesMoved (pending_range_moves);
        }
+       
+       clear_pending ();
 
+       in_flush = false;
+}
+
+void
+Playlist::clear_pending ()
+{
        pending_adds.clear ();
        pending_removes.clear ();
        pending_bounds.clear ();
        pending_range_moves.clear ();
-
-       in_flush = false;
+       pending_contents_change = false;
+       pending_length = false;
 }
 
 /*************************************************************
@@ -478,26 +660,26 @@ Playlist::flush_notifications ()
  *************************************************************/
 
 void
-Playlist::add_region (boost::shared_ptr<Region> region, nframes_t position, float times, bool auto_partition) 
+Playlist::add_region (boost::shared_ptr<Region> region, framepos_t position, float times, bool auto_partition)
 {
        RegionLock rlock (this);
        times = fabs (times);
-       
+
        int itimes = (int) floor (times);
 
-       nframes_t pos = position;
+       framepos_t pos = position;
 
-       if(times == 1 && auto_partition){
-               partition(pos, (nframes_t) (pos + region->length()), true);
+       if (times == 1 && auto_partition){
+               partition(pos, (pos + region->length()), true);
        }
-       
+
        if (itimes >= 1) {
                add_region_internal (region, pos);
                pos += region->length();
                --itimes;
        }
-       
-       
+
+
        /* note that itimes can be zero if we being asked to just
           insert a single fraction of the region.
        */
@@ -507,15 +689,25 @@ Playlist::add_region (boost::shared_ptr<Region> region, nframes_t position, floa
                add_region_internal (copy, pos);
                pos += region->length();
        }
-       
-       nframes_t length = 0;
+
+       framecnt_t length = 0;
 
        if (floor (times) != times) {
-               length = (nframes_t) floor (region->length() * (times - floor (times)));
+               length = (framecnt_t) floor (region->length() * (times - floor (times)));
                string name;
-               _session.region_name (name, region->name(), false);
-               boost::shared_ptr<Region> sub = RegionFactory::create (region, 0, length, name, region->layer(), region->flags());
-               add_region_internal (sub, pos);
+               RegionFactory::region_name (name, region->name(), false);
+
+               {
+                       PropertyList plist;
+                       
+                       plist.add (Properties::start, region->start());
+                       plist.add (Properties::length, length);
+                       plist.add (Properties::name, name);
+                       plist.add (Properties::layer, region->layer());
+
+                       boost::shared_ptr<Region> sub = RegionFactory::create (region, plist);
+                       add_region_internal (sub, pos);
+               }
        }
 
        possibly_splice_unlocked (position, (pos + length) - position, boost::shared_ptr<Region>());
@@ -534,15 +726,15 @@ Playlist::set_region_ownership ()
 }
 
 bool
-Playlist::add_region_internal (boost::shared_ptr<Region> region, nframes_t position)
+Playlist::add_region_internal (boost::shared_ptr<Region> region, framepos_t position)
 {
        if (region->data_type() != _type){
                return false;
        }
 
        RegionSortByPosition cmp;
-       
-       nframes_t old_length = 0;
+
+       framecnt_t old_length = 0;
 
        if (!holding_state()) {
                 old_length = _get_maximum_extent();
@@ -551,7 +743,7 @@ Playlist::add_region_internal (boost::shared_ptr<Region> region, nframes_t posit
        if (!first_set_state) {
                boost::shared_ptr<Playlist> foo (shared_from_this());
                region->set_playlist (boost::weak_ptr<Playlist>(foo));
-       } 
+       }
 
        region->set_position (position, this);
 
@@ -562,15 +754,15 @@ Playlist::add_region_internal (boost::shared_ptr<Region> region, nframes_t posit
 
        possibly_splice_unlocked (position, region->length(), region);
 
-       if (!holding_state () && !in_set_state) {
-               /* layers get assigned from XML state */
+       if (!holding_state ()) {
+               /* layers get assigned from XML state, and are not reset during undo/redo */
                relayer ();
        }
 
        /* we need to notify the existence of new region before checking dependents. Ick. */
 
        notify_region_added (region);
-       
+
        if (!holding_state ()) {
 
                check_dependents (region, false);
@@ -580,16 +772,13 @@ Playlist::add_region_internal (boost::shared_ptr<Region> region, nframes_t posit
                }
        }
 
-       region_state_changed_connections.push_back (
-               region->StateChanged.connect (sigc::bind (mem_fun (this, &Playlist::region_changed_proxy), 
-                                                         boost::weak_ptr<Region> (region)))
-               );
+       region->PropertyChanged.connect_same_thread (region_state_changed_connections, boost::bind (&Playlist::region_changed_proxy, this, _1, boost::weak_ptr<Region> (region)));
 
        return true;
 }
 
 void
-Playlist::replace_region (boost::shared_ptr<Region> old, boost::shared_ptr<Region> newr, nframes_t pos)
+Playlist::replace_region (boost::shared_ptr<Region> old, boost::shared_ptr<Region> newr, framepos_t pos)
 {
        RegionLock rlock (this);
 
@@ -601,7 +790,7 @@ Playlist::replace_region (boost::shared_ptr<Region> old, boost::shared_ptr<Regio
 
        _splicing = old_sp;
 
-       possibly_splice_unlocked (pos, (nframes64_t) old->length() - (nframes64_t) newr->length());
+       possibly_splice_unlocked (pos, old->length() - newr->length());
 }
 
 void
@@ -615,7 +804,8 @@ int
 Playlist::remove_region_internal (boost::shared_ptr<Region> region)
 {
        RegionList::iterator i;
-       nframes_t old_length = 0;
+       framecnt_t old_length = 0;
+       int ret = -1;
 
        if (!holding_state()) {
                old_length = _get_maximum_extent();
@@ -626,33 +816,36 @@ Playlist::remove_region_internal (boost::shared_ptr<Region> region)
                region->set_playlist (boost::weak_ptr<Playlist>());
        }
 
+       /* XXX should probably freeze here .... */
+
        for (i = regions.begin(); i != regions.end(); ++i) {
                if (*i == region) {
 
-                       nframes_t pos = (*i)->position();
-                       nframes64_t distance = (*i)->length();
+                       framepos_t pos = (*i)->position();
+                       framecnt_t distance = (*i)->length();
 
                        regions.erase (i);
 
                        possibly_splice_unlocked (pos, -distance);
 
                        if (!holding_state ()) {
-                               relayer ();
+                                relayer ();
                                remove_dependents (region);
-                               
+
                                if (old_length != _get_maximum_extent()) {
                                        notify_length_changed ();
                                }
                        }
 
                        notify_region_removed (region);
-                       return 0;
+                       ret = 0;
+                       break;
                }
        }
 
+       /* XXX and thaw ... */
 
-
-       return -1;
+       return ret;
 }
 
 void
@@ -685,19 +878,19 @@ Playlist::get_region_list_equivalent_regions (boost::shared_ptr<Region> other, v
 }
 
 void
-Playlist::partition (nframes_t start, nframes_t end, bool cut)
+Playlist::partition (framepos_t start, framepos_t end, bool cut)
 {
        RegionList thawlist;
 
        partition_internal (start, end, cut, thawlist);
 
        for (RegionList::iterator i = thawlist.begin(); i != thawlist.end(); ++i) {
-               (*i)->thaw ("separation");
+               (*i)->resume_property_changes ();
        }
 }
 
 void
-Playlist::partition_internal (nframes_t start, nframes_t end, bool cutting, RegionList& thawlist)
+Playlist::partition_internal (framepos_t start, framepos_t end, bool cutting, RegionList& thawlist)
 {
        RegionList new_regions;
 
@@ -709,21 +902,21 @@ Playlist::partition_internal (nframes_t start, nframes_t end, bool cutting, Regi
                string new_name;
                RegionList::iterator tmp;
                OverlapType overlap;
-               nframes_t pos1, pos2, pos3, pos4;
-               
+               framepos_t pos1, pos2, pos3, pos4;
+
                in_partition = true;
-               
+
                /* need to work from a copy, because otherwise the regions we add during the process
                   get operated on as well.
                */
-               
-               RegionList copy = regions;
-               
+
+               RegionList copy = regions.rlist();
+
                for (RegionList::iterator i = copy.begin(); i != copy.end(); i = tmp) {
 
                        tmp = i;
                        ++tmp;
-                       
+
                        current = *i;
 
                        if (current->first_frame() >= start && current->last_frame() < end) {
@@ -734,7 +927,7 @@ Playlist::partition_internal (nframes_t start, nframes_t end, bool cutting, Regi
 
                                continue;
                        }
-                       
+
                        /* coverage will return OverlapStart if the start coincides
                           with the end point. we do not partition such a region,
                           so catch this special case.
@@ -752,12 +945,12 @@ Playlist::partition_internal (nframes_t start, nframes_t end, bool cutting, Regi
                        pos2 = start;
                        pos3 = end;
                        pos4 = current->last_frame();
-                       
+
                        if (overlap == OverlapInternal) {
                                /* split: we need 3 new regions, the front, middle and end.
                                   cut:   we need 2 regions, the front and end.
                                */
-                               
+
                                /*
                                         start                 end
                          ---------------*************************------------
@@ -766,31 +959,50 @@ Playlist::partition_internal (nframes_t start, nframes_t end, bool cutting, Regi
                          ---------------*****++++++++++++++++====------------
                          CUT
                          ---------------*****----------------====------------
-                         
+
                                */
 
                                if (!cutting) {
                                        /* "middle" ++++++ */
+
+                                       RegionFactory::region_name (new_name, current->name(), false);
+
+                                       PropertyList plist;
                                        
-                                       _session.region_name (new_name, current->name(), false);
-                                       region = RegionFactory::create (current, pos2 - pos1, pos3 - pos2, new_name,
-                                                                       regions.size(), Region::Flag(current->flags()|Region::Automatic|Region::LeftOfSplit|Region::RightOfSplit));
+                                       plist.add (Properties::start, current->start() + (pos2 - pos1));
+                                       plist.add (Properties::length, pos3 - pos2);
+                                       plist.add (Properties::name, new_name);
+                                       plist.add (Properties::layer, regions.size());
+                                       plist.add (Properties::automatic, true);
+                                       plist.add (Properties::left_of_split, true);
+                                       plist.add (Properties::right_of_split, true);
+
+                                       region = RegionFactory::create (current, plist);
                                        add_region_internal (region, start);
                                        new_regions.push_back (region);
                                }
-                               
+
                                /* "end" ====== */
-                       
-                               _session.region_name (new_name, current->name(), false);
-                               region = RegionFactory::create (current, pos3 - pos1, pos4 - pos3, new_name, 
-                                                               regions.size(), Region::Flag(current->flags()|Region::Automatic|Region::RightOfSplit));
+
+                               RegionFactory::region_name (new_name, current->name(), false);
+
+                               PropertyList plist;
+                               
+                               plist.add (Properties::start, current->start() + (pos3 - pos1));
+                               plist.add (Properties::length, pos4 - pos3);
+                               plist.add (Properties::name, new_name);
+                               plist.add (Properties::layer, regions.size());
+                               plist.add (Properties::automatic, true);
+                               plist.add (Properties::right_of_split, true);
+                               
+                               region = RegionFactory::create (current, plist);
 
                                add_region_internal (region, end);
                                new_regions.push_back (region);
-                               
+
                                /* "front" ***** */
-                               
-                               current->freeze ();
+
+                               current->suspend_property_changes ();
                                thawlist.push_back (current);
                                current->trim_end (pos2, this);
 
@@ -800,27 +1012,36 @@ Playlist::partition_internal (nframes_t start, nframes_t end, bool cutting, Regi
                                                              start           end
                                    ---------------*************************------------
                                                   P1           P2         P4   P3
-                                    SPLIT:                                                
+                                    SPLIT:
                                    ---------------**************+++++++++++------------
-                                    CUT:                                                  
+                                    CUT:
                                    ---------------**************-----------------------
                                */
-                               
+
                                if (!cutting) {
 
                                        /* end +++++ */
+
+                                       RegionFactory::region_name (new_name, current->name(), false);
+                                       
+                                       PropertyList plist;
                                        
-                                       _session.region_name (new_name, current->name(), false);
-                                       region = RegionFactory::create (current, pos2 - pos1, pos4 - pos2, new_name, (layer_t) regions.size(),
-                                                                       Region::Flag(current->flags()|Region::Automatic|Region::LeftOfSplit));
+                                       plist.add (Properties::start, current->start() + (pos2 - pos1));
+                                       plist.add (Properties::length, pos4 - pos2);
+                                       plist.add (Properties::name, new_name);
+                                       plist.add (Properties::layer, regions.size());
+                                       plist.add (Properties::automatic, true);
+                                       plist.add (Properties::left_of_split, true);
+
+                                       region = RegionFactory::create (current, plist);
 
                                        add_region_internal (region, start);
                                        new_regions.push_back (region);
                                }
-                               
+
                                /* front ****** */
-                               
-                               current->freeze ();
+
+                               current->suspend_property_changes ();
                                thawlist.push_back (current);
                                current->trim_end (pos2, this);
 
@@ -829,32 +1050,41 @@ Playlist::partition_internal (nframes_t start, nframes_t end, bool cutting, Regi
                                /* split: we need 2 regions: the front and the end.
                                   cut: just trim current to skip the cut area
                                */
-                               
+
                                /*
                                                        start           end
                                    ---------------*************************------------
-                                      P2          P1 P3                   P4          
+                                      P2          P1 P3                   P4
 
                                    SPLIT:
                                    ---------------****+++++++++++++++++++++------------
                                    CUT:
                                    -------------------*********************------------
-                                   
+
                                */
 
                                if (!cutting) {
                                        /* front **** */
-                                       _session.region_name (new_name, current->name(), false);
-                                       region = RegionFactory::create (current, 0, pos3 - pos1, new_name,
-                                                                       regions.size(), Region::Flag(current->flags()|Region::Automatic|Region::RightOfSplit));
+                                       RegionFactory::region_name (new_name, current->name(), false);
+
+                                       PropertyList plist;
+                                       
+                                       plist.add (Properties::start, current->start());
+                                       plist.add (Properties::length, pos3 - pos1);
+                                       plist.add (Properties::name, new_name);
+                                       plist.add (Properties::layer, regions.size());
+                                       plist.add (Properties::automatic, true);
+                                       plist.add (Properties::right_of_split, true);
+
+                                       region = RegionFactory::create (current, plist);
 
                                        add_region_internal (region, pos1);
                                        new_regions.push_back (region);
-                               } 
-                               
+                               }
+
                                /* end */
-                               
-                               current->freeze ();
+
+                               current->suspend_property_changes ();
                                thawlist.push_back (current);
                                current->trim_front (pos3, this);
                        } else if (overlap == OverlapExternal) {
@@ -862,19 +1092,19 @@ Playlist::partition_internal (nframes_t start, nframes_t end, bool cutting, Regi
                                /* split: no split required.
                                   cut: remove the region.
                                */
-                               
+
                                /*
                                       start                                      end
                                    ---------------*************************------------
-                                      P2          P1 P3                   P4          
+                                      P2          P1 P3                   P4
 
                                    SPLIT:
                                    ---------------*************************------------
                                    CUT:
                                    ----------------------------------------------------
-                                   
+
                                */
-                               
+
                                if (cutting) {
                                        remove_region_internal (current);
                                }
@@ -892,11 +1122,11 @@ Playlist::partition_internal (nframes_t start, nframes_t end, bool cutting, Regi
 }
 
 boost::shared_ptr<Playlist>
-Playlist::cut_copy (boost::shared_ptr<Playlist> (Playlist::*pmf)(nframes_t, nframes_t,bool), list<AudioRange>& ranges, bool result_is_hidden)
+Playlist::cut_copy (boost::shared_ptr<Playlist> (Playlist::*pmf)(framepos_t, framecnt_t,bool), list<AudioRange>& ranges, bool result_is_hidden)
 {
        boost::shared_ptr<Playlist> ret;
        boost::shared_ptr<Playlist> pl;
-       nframes_t start;
+       framepos_t start;
 
        if (ranges.empty()) {
                return boost::shared_ptr<Playlist>();
@@ -907,11 +1137,11 @@ Playlist::cut_copy (boost::shared_ptr<Playlist> (Playlist::*pmf)(nframes_t, nfra
        for (list<AudioRange>::iterator i = ranges.begin(); i != ranges.end(); ++i) {
 
                pl = (this->*pmf)((*i).start, (*i).length(), result_is_hidden);
-               
+
                if (i == ranges.begin()) {
                        ret = pl;
                } else {
-                       
+
                        /* paste the next section into the nascent playlist,
                           offset to reflect the start of the first range we
                           chopped.
@@ -927,19 +1157,19 @@ Playlist::cut_copy (boost::shared_ptr<Playlist> (Playlist::*pmf)(nframes_t, nfra
 boost::shared_ptr<Playlist>
 Playlist::cut (list<AudioRange>& ranges, bool result_is_hidden)
 {
-       boost::shared_ptr<Playlist> (Playlist::*pmf)(nframes_t,nframes_t,bool) = &Playlist::cut;
+       boost::shared_ptr<Playlist> (Playlist::*pmf)(framepos_t,framecnt_t,bool) = &Playlist::cut;
        return cut_copy (pmf, ranges, result_is_hidden);
 }
 
 boost::shared_ptr<Playlist>
 Playlist::copy (list<AudioRange>& ranges, bool result_is_hidden)
 {
-       boost::shared_ptr<Playlist> (Playlist::*pmf)(nframes_t,nframes_t,bool) = &Playlist::copy;
+       boost::shared_ptr<Playlist> (Playlist::*pmf)(framepos_t,framecnt_t,bool) = &Playlist::copy;
        return cut_copy (pmf, ranges, result_is_hidden);
 }
 
 boost::shared_ptr<Playlist>
-Playlist::cut (nframes_t start, nframes_t cnt, bool result_is_hidden)
+Playlist::cut (framepos_t start, framecnt_t cnt, bool result_is_hidden)
 {
        boost::shared_ptr<Playlist> the_copy;
        RegionList thawlist;
@@ -957,17 +1187,17 @@ Playlist::cut (nframes_t start, nframes_t cnt, bool result_is_hidden)
        partition_internal (start, start+cnt-1, true, thawlist);
 
        for (RegionList::iterator i = thawlist.begin(); i != thawlist.end(); ++i) {
-               (*i)->thaw ("playlist cut");
+               (*i)->resume_property_changes();
        }
 
        return the_copy;
 }
 
 boost::shared_ptr<Playlist>
-Playlist::copy (nframes_t start, nframes_t cnt, bool result_is_hidden)
+Playlist::copy (framepos_t start, framecnt_t cnt, bool result_is_hidden)
 {
        char buf[32];
-       
+
        snprintf (buf, sizeof (buf), "%" PRIu32, ++subcnt);
        string new_name = _name;
        new_name += '.';
@@ -978,20 +1208,19 @@ Playlist::copy (nframes_t start, nframes_t cnt, bool result_is_hidden)
 }
 
 int
-Playlist::paste (boost::shared_ptr<Playlist> other, nframes_t position, float times)
+Playlist::paste (boost::shared_ptr<Playlist> other, framepos_t position, float times)
 {
        times = fabs (times);
-       nframes_t old_length;
 
        {
                RegionLock rl1 (this);
                RegionLock rl2 (other.get());
 
-               old_length = _get_maximum_extent();
-       
+               framecnt_t old_length = _get_maximum_extent();
+
                int itimes = (int) floor (times);
-               nframes_t pos = position;
-               nframes_t shift = other->_get_maximum_extent();
+               framepos_t pos = position;
+               framecnt_t shift = other->_get_maximum_extent();
                layer_t top_layer = regions.size();
 
                while (itimes--) {
@@ -1001,7 +1230,7 @@ Playlist::paste (boost::shared_ptr<Playlist> other, nframes_t position, float ti
                                /* put these new regions on top of all existing ones, but preserve
                                   the ordering they had in the original playlist.
                                */
-                               
+
                                copy_of_region->set_layer (copy_of_region->layer() + top_layer);
                                add_region_internal (copy_of_region, copy_of_region->position() + pos);
                        }
@@ -1015,7 +1244,7 @@ Playlist::paste (boost::shared_ptr<Playlist> other, nframes_t position, float ti
                        notify_length_changed ();
                }
 
-               
+
        }
 
        return 0;
@@ -1023,13 +1252,13 @@ Playlist::paste (boost::shared_ptr<Playlist> other, nframes_t position, float ti
 
 
 void
-Playlist::duplicate (boost::shared_ptr<Region> region, nframes_t position, float times)
+Playlist::duplicate (boost::shared_ptr<Region> region, framepos_t position, float times)
 {
        times = fabs (times);
 
        RegionLock rl (this);
        int itimes = (int) floor (times);
-       nframes_t pos = position;
+       framepos_t pos = position;
 
        while (itimes--) {
                boost::shared_ptr<Region> copy = RegionFactory::create (region);
@@ -1038,19 +1267,28 @@ Playlist::duplicate (boost::shared_ptr<Region> region, nframes_t position, float
        }
 
        if (floor (times) != times) {
-               nframes_t length = (nframes_t) floor (region->length() * (times - floor (times)));
+               framecnt_t length = (framecnt_t) floor (region->length() * (times - floor (times)));
                string name;
-               _session.region_name (name, region->name(), false);
-               boost::shared_ptr<Region> sub = RegionFactory::create (region, 0, length, name, region->layer(), region->flags());
-               add_region_internal (sub, pos);
+               RegionFactory::region_name (name, region->name(), false);
+               
+               {
+                       PropertyList plist;
+                       
+                       plist.add (Properties::start, region->start());
+                       plist.add (Properties::length, length);
+                       plist.add (Properties::name, name);
+                       
+                       boost::shared_ptr<Region> sub = RegionFactory::create (region, plist);
+                       add_region_internal (sub, pos);
+               }
        }
 }
 
 void
-Playlist::shift (nframes64_t at, nframes64_t distance, bool move_intersected, bool ignore_music_glue)
+Playlist::shift (framepos_t at, frameoffset_t distance, bool move_intersected, bool ignore_music_glue)
 {
        RegionLock rlock (this);
-       RegionList copy (regions);
+       RegionList copy (regions.rlist());
        RegionList fixup;
 
        for (RegionList::iterator r = copy.begin(); r != copy.end(); ++r) {
@@ -1059,14 +1297,14 @@ Playlist::shift (nframes64_t at, nframes64_t distance, bool move_intersected, bo
                        /* too early */
                        continue;
                }
-               
+
                if (at > (*r)->first_frame() && at < (*r)->last_frame()) {
                        /* intersected region */
                        if (!move_intersected) {
                                continue;
                        }
                }
-               
+
                /* do not move regions glued to music time - that
                   has to be done separately.
                */
@@ -1085,10 +1323,10 @@ Playlist::shift (nframes64_t at, nframes64_t distance, bool move_intersected, bo
 }
 
 void
-Playlist::split (nframes64_t at)
+Playlist::split (framepos_t at)
 {
        RegionLock rlock (this);
-       RegionList copy (regions);
+       RegionList copy (regions.rlist());
 
        /* use a copy since this operation can modify the region list
         */
@@ -1099,14 +1337,14 @@ Playlist::split (nframes64_t at)
 }
 
 void
-Playlist::split_region (boost::shared_ptr<Region> region, nframes_t playlist_position)
+Playlist::split_region (boost::shared_ptr<Region> region, framepos_t playlist_position)
 {
        RegionLock rl (this);
        _split_region (region, playlist_position);
 }
 
 void
-Playlist::_split_region (boost::shared_ptr<Region> region, nframes_t playlist_position)
+Playlist::_split_region (boost::shared_ptr<Region> region, framepos_t playlist_position)
 {
        if (!region->covers (playlist_position)) {
                return;
@@ -1119,24 +1357,44 @@ Playlist::_split_region (boost::shared_ptr<Region> region, nframes_t playlist_po
 
        boost::shared_ptr<Region> left;
        boost::shared_ptr<Region> right;
-       nframes_t before;
-       nframes_t after;
+       frameoffset_t before;
+       frameoffset_t after;
        string before_name;
        string after_name;
 
        /* split doesn't change anything about length, so don't try to splice */
-       
+
        bool old_sp = _splicing;
        _splicing = true;
 
        before = playlist_position - region->position();
        after = region->length() - before;
-       
-       _session.region_name (before_name, region->name(), false);
-       left = RegionFactory::create (region, 0, before, before_name, region->layer(), Region::Flag (region->flags()|Region::LeftOfSplit));
 
-       _session.region_name (after_name, region->name(), false);
-       right = RegionFactory::create (region, before, after, after_name, region->layer(), Region::Flag (region->flags()|Region::RightOfSplit));
+       RegionFactory::region_name (before_name, region->name(), false);
+
+       {
+               PropertyList plist;
+               
+               plist.add (Properties::start, region->start());
+               plist.add (Properties::length, before);
+               plist.add (Properties::name, before_name);
+               plist.add (Properties::left_of_split, true);
+               
+               left = RegionFactory::create (region, plist);
+       }
+
+       RegionFactory::region_name (after_name, region->name(), false);
+
+       {
+               PropertyList plist;
+               
+               plist.add (Properties::start, region->start() + before);
+               plist.add (Properties::length, after);
+               plist.add (Properties::name, after_name);
+               plist.add (Properties::right_of_split, true);
+
+               right = RegionFactory::create (region, plist);
+       }
 
        add_region_internal (left, region->position());
        add_region_internal (right, region->position() + before);
@@ -1147,21 +1405,21 @@ Playlist::_split_region (boost::shared_ptr<Region> region, nframes_t playlist_po
                        (*i)->set_last_layer_op( (*i)->last_layer_op() + 1 );
                }
        }
-       
+
        left->set_last_layer_op ( orig_layer_op );
        right->set_last_layer_op ( orig_layer_op + 1);
 
        layer_op_counter++;
 
        finalize_split_region (region, left, right);
-       
+
        remove_region_internal (region);
 
        _splicing = old_sp;
 }
 
 void
-Playlist::possibly_splice (nframes_t at, nframes64_t distance, boost::shared_ptr<Region> exclude)
+Playlist::possibly_splice (framepos_t at, framecnt_t distance, boost::shared_ptr<Region> exclude)
 {
        if (_splicing || in_set_state) {
                /* don't respond to splicing moves or state setting */
@@ -1174,7 +1432,7 @@ Playlist::possibly_splice (nframes_t at, nframes64_t distance, boost::shared_ptr
 }
 
 void
-Playlist::possibly_splice_unlocked (nframes_t at, nframes64_t distance, boost::shared_ptr<Region> exclude)
+Playlist::possibly_splice_unlocked (framepos_t at, framecnt_t distance, boost::shared_ptr<Region> exclude)
 {
        if (_splicing || in_set_state) {
                /* don't respond to splicing moves or state setting */
@@ -1187,7 +1445,7 @@ Playlist::possibly_splice_unlocked (nframes_t at, nframes64_t distance, boost::s
 }
 
 void
-Playlist::splice_locked (nframes_t at, nframes64_t distance, boost::shared_ptr<Region> exclude)
+Playlist::splice_locked (framepos_t at, framecnt_t distance, boost::shared_ptr<Region> exclude)
 {
        {
                RegionLock rl (this);
@@ -1196,13 +1454,13 @@ Playlist::splice_locked (nframes_t at, nframes64_t distance, boost::shared_ptr<R
 }
 
 void
-Playlist::splice_unlocked (nframes_t at, nframes64_t distance, boost::shared_ptr<Region> exclude)
+Playlist::splice_unlocked (framepos_t at, framecnt_t distance, boost::shared_ptr<Region> exclude)
 {
        core_splice (at, distance, exclude);
 }
 
 void
-Playlist::core_splice (nframes_t at, nframes64_t distance, boost::shared_ptr<Region> exclude)
+Playlist::core_splice (framepos_t at, framecnt_t distance, boost::shared_ptr<Region> exclude)
 {
        _splicing = true;
 
@@ -1213,13 +1471,13 @@ Playlist::core_splice (nframes_t at, nframes64_t distance, boost::shared_ptr<Reg
                }
 
                if ((*i)->position() >= at) {
-                       nframes64_t new_pos = (*i)->position() + distance;
+                       framepos_t new_pos = (*i)->position() + distance;
                        if (new_pos < 0) {
                                new_pos = 0;
                        } else if (new_pos >= max_frames - (*i)->length()) {
                                new_pos = max_frames - (*i)->length();
-                       } 
-                               
+                       }
+
                        (*i)->set_position (new_pos, this);
                }
        }
@@ -1230,26 +1488,27 @@ Playlist::core_splice (nframes_t at, nframes64_t distance, boost::shared_ptr<Reg
 }
 
 void
-Playlist::region_bounds_changed (Change what_changed, boost::shared_ptr<Region> region)
+Playlist::region_bounds_changed (const PropertyChange& what_changed, boost::shared_ptr<Region> region)
 {
        if (in_set_state || _splicing || _nudging || _shuffling) {
                return;
        }
 
-       if (what_changed & ARDOUR::PositionChanged) {
+       if (what_changed.contains (Properties::position)) {
 
                /* remove it from the list then add it back in
                   the right place again.
                */
-               
+
                RegionSortByPosition cmp;
 
                RegionList::iterator i = find (regions.begin(), regions.end(), region);
-               
+
                if (i == regions.end()) {
-                       warning << string_compose (_("%1: bounds changed received for region (%2)not in playlist"),
-                                           _name, region->name())
-                               << endmsg;
+                        /* the region bounds are being modified but its not currently
+                           in the region list. we will use its bounds correctly when/if
+                           it is added
+                        */
                        return;
                }
 
@@ -1257,17 +1516,17 @@ Playlist::region_bounds_changed (Change what_changed, boost::shared_ptr<Region>
                regions.insert (upper_bound (regions.begin(), regions.end(), region, cmp), region);
        }
 
-       if (what_changed & Change (ARDOUR::PositionChanged|ARDOUR::LengthChanged)) {
-               
-               nframes64_t delta = 0;
-               
-               if (what_changed & ARDOUR::PositionChanged) {
-                       delta = (nframes64_t) region->position() - (nframes64_t) region->last_position();
-               } 
-               
-               if (what_changed & ARDOUR::LengthChanged) {
-                       delta += (nframes64_t) region->length() - (nframes64_t) region->last_length();
-               } 
+       if (what_changed.contains (Properties::position) || what_changed.contains (Properties::length)) {
+
+               frameoffset_t delta = 0;
+
+               if (what_changed.contains (Properties::position)) {
+                       delta = region->position() - region->last_position();
+               }
+
+               if (what_changed.contains (Properties::length)) {
+                       delta += region->length() - region->last_length();
+               }
 
                if (delta) {
                        possibly_splice (region->last_position() + region->last_length(), delta, region);
@@ -1280,7 +1539,7 @@ Playlist::region_bounds_changed (Change what_changed, boost::shared_ptr<Region>
                                /* it moved or changed length, so change the timestamp */
                                timestamp_layer_op (region);
                        }
-                       
+
                        notify_length_changed ();
                        relayer ();
                        check_dependents (region, false);
@@ -1289,7 +1548,7 @@ Playlist::region_bounds_changed (Change what_changed, boost::shared_ptr<Region>
 }
 
 void
-Playlist::region_changed_proxy (Change what_changed, boost::weak_ptr<Region> weak_region)
+Playlist::region_changed_proxy (const PropertyChange& what_changed, boost::weak_ptr<Region> weak_region)
 {
        boost::shared_ptr<Region> region (weak_region.lock());
 
@@ -1297,37 +1556,53 @@ Playlist::region_changed_proxy (Change what_changed, boost::weak_ptr<Region> wea
                return;
        }
 
-
        /* this makes a virtual call to the right kind of playlist ... */
 
        region_changed (what_changed, region);
 }
 
 bool
-Playlist::region_changed (Change what_changed, boost::shared_ptr<Region> region)
+Playlist::region_changed (const PropertyChange& what_changed, boost::shared_ptr<Region> region)
 {
-       Change our_interests = Change (Region::MuteChanged|Region::LayerChanged|Region::OpacityChanged);
+       PropertyChange our_interests;
+       PropertyChange bounds;
+       PropertyChange pos_and_length;
        bool save = false;
 
        if (in_set_state || in_flush) {
                return false;
        }
 
-       if (what_changed & BoundsChanged) {
+       our_interests.add (Properties::muted);
+       our_interests.add (Properties::layer);
+       our_interests.add (Properties::opaque);
+
+       bounds.add (Properties::start);
+       bounds.add (Properties::position);
+       bounds.add (Properties::length);
+
+       pos_and_length.add (Properties::position);
+       pos_and_length.add (Properties::length);
+
+       if (what_changed.contains (bounds)) {
                region_bounds_changed (what_changed, region);
                save = !(_splicing || _nudging);
        }
-               
-       if ((what_changed & our_interests) && 
-           !(what_changed & Change (ARDOUR::PositionChanged|ARDOUR::LengthChanged))) {
+
+       if (what_changed.contains (our_interests) && !what_changed.contains (pos_and_length)) {
                check_dependents (region, false);
        }
 
-       if (what_changed & Change (ARDOUR::PositionChanged)) {
+       if (what_changed.contains (Properties::position)) {
                notify_region_moved (region);
        }
-               
-       if (what_changed & our_interests) {
+
+
+       /* don't notify about layer changes, since we are the only object that can initiate
+          them, and we notify in ::relayer()
+       */
+
+       if (what_changed.contains (our_interests)) {
                save = true;
        }
 
@@ -1348,26 +1623,30 @@ Playlist::clear (bool with_signals)
        {
                RegionLock rl (this);
 
-               for (
-                       std::list<sigc::connection>::iterator i = region_state_changed_connections.begin ();
-                       i != region_state_changed_connections.end ();
-                       ++i
-               ) {
-                       i->disconnect ();       
-               }
-                    
+               region_state_changed_connections.drop_connections ();
+
                for (RegionList::iterator i = regions.begin(); i != regions.end(); ++i) {
                        pending_removes.insert (*i);
                }
 
                regions.clear ();
+
+                for (set<boost::shared_ptr<Region> >::iterator s = pending_removes.begin(); s != pending_removes.end(); ++s) {
+                        remove_dependents (*s);
+                }
        }
 
        if (with_signals) {
+
+                for (set<boost::shared_ptr<Region> >::iterator s = pending_removes.begin(); s != pending_removes.end(); ++s) {
+                        RegionRemoved (boost::weak_ptr<Region> (*s)); /* EMIT SIGNAL */
+                }
+
+                pending_removes.clear ();
                pending_length = false;
                LengthChanged ();
-               pending_modified = false;
-               Modified ();
+               pending_contents_change = false;
+               ContentsChanged ();
        }
 
 }
@@ -1377,40 +1656,70 @@ Playlist::clear (bool with_signals)
  **********************************************************************/
 
 Playlist::RegionList *
-Playlist::regions_at (nframes_t frame)
+Playlist::regions_at (framepos_t frame)
 
 {
        RegionLock rlock (this);
        return find_regions_at (frame);
-}      
+}
 
 boost::shared_ptr<Region>
-Playlist::top_region_at (nframes_t frame)
+Playlist::top_region_at (framepos_t frame)
 
 {
        RegionLock rlock (this);
        RegionList *rlist = find_regions_at (frame);
        boost::shared_ptr<Region> region;
-       
+
        if (rlist->size()) {
                RegionSortByLayer cmp;
                rlist->sort (cmp);
                region = rlist->back();
-       } 
+       }
+
+       delete rlist;
+       return region;
+}
+
+boost::shared_ptr<Region>
+Playlist::top_unmuted_region_at (framepos_t frame)
+
+{
+       RegionLock rlock (this);
+       RegionList *rlist = find_regions_at (frame);
+
+       for (RegionList::iterator i = rlist->begin(); i != rlist->end(); ) {
+
+               RegionList::iterator tmp = i;
+               ++tmp;
+
+               if ((*i)->muted()) {
+                       rlist->erase (i);
+               }
+
+               i = tmp;
+       }
+
+       boost::shared_ptr<Region> region;
+
+       if (rlist->size()) {
+               RegionSortByLayer cmp;
+               rlist->sort (cmp);
+               region = rlist->back();
+       }
 
        delete rlist;
        return region;
-}      
+}
 
 Playlist::RegionList*
-Playlist::regions_to_read (nframes_t start, nframes_t end)
+Playlist::regions_to_read (framepos_t start, framepos_t end)
 {
        /* Caller must hold lock */
 
        RegionList covering;
-       set<nframes_t> to_check;
+       set<framepos_t> to_check;
        set<boost::shared_ptr<Region> > unique;
-       RegionList here;
 
        to_check.insert (start);
        to_check.insert (end);
@@ -1458,45 +1767,46 @@ Playlist::regions_to_read (nframes_t start, nframes_t end)
        if (covering.size() == 1) {
 
                rlist->push_back (covering.front());
-               
+
        } else {
-       
-               for (set<nframes_t>::iterator t = to_check.begin(); t != to_check.end(); ++t) {
-                       
+
+               RegionList here;
+               for (set<framepos_t>::iterator t = to_check.begin(); t != to_check.end(); ++t) {
+
                        here.clear ();
-                       
+
                        for (RegionList::iterator x = covering.begin(); x != covering.end(); ++x) {
-                       
+
                                if ((*x)->covers (*t)) {
                                        here.push_back (*x);
                                }
                        }
-                       
+
                        RegionSortByLayer cmp;
                        here.sort (cmp);
-                       
+
                        /* ... and get the top/transparent regions at "here" */
-                       
+
                        for (RegionList::reverse_iterator c = here.rbegin(); c != here.rend(); ++c) {
-                               
+
                                unique.insert (*c);
-                               
+
                                if ((*c)->opaque()) {
-                                       
+
                                        /* the other regions at this position are hidden by this one */
-                                       
+
                                        break;
                                }
                        }
                }
-               
+
                for (set<boost::shared_ptr<Region> >::iterator s = unique.begin(); s != unique.end(); ++s) {
                        rlist->push_back (*s);
                }
 
                if (rlist->size() > 1) {
                        /* now sort by time order */
-                       
+
                        RegionSortByPosition cmp;
                        rlist->sort (cmp);
                }
@@ -1506,7 +1816,7 @@ Playlist::regions_to_read (nframes_t start, nframes_t end)
 }
 
 Playlist::RegionList *
-Playlist::find_regions_at (nframes_t frame)
+Playlist::find_regions_at (framepos_t frame)
 {
        /* Caller must hold lock */
 
@@ -1522,7 +1832,7 @@ Playlist::find_regions_at (nframes_t frame)
 }
 
 Playlist::RegionList *
-Playlist::regions_touched (nframes_t start, nframes_t end)
+Playlist::regions_touched (framepos_t start, framepos_t end)
 {
        RegionLock rlock (this);
        RegionList *rlist = new RegionList;
@@ -1536,8 +1846,8 @@ Playlist::regions_touched (nframes_t start, nframes_t end)
        return rlist;
 }
 
-nframes64_t
-Playlist::find_next_transient (nframes64_t from, int dir)
+framepos_t
+Playlist::find_next_transient (framepos_t from, int dir)
 {
        RegionLock rlock (this);
        AnalysisFeatureList points;
@@ -1557,26 +1867,26 @@ Playlist::find_next_transient (nframes64_t from, int dir)
                (*i)->get_transients (these_points);
 
                /* add first frame, just, err, because */
-               
+
                these_points.push_back ((*i)->first_frame());
-               
+
                points.insert (points.end(), these_points.begin(), these_points.end());
                these_points.clear ();
        }
-       
+
        if (points.empty()) {
                return -1;
        }
 
        TransientDetector::cleanup_transients (points, _session.frame_rate(), 3.0);
        bool reached = false;
-       
+
        if (dir > 0) {
                for (AnalysisFeatureList::iterator x = points.begin(); x != points.end(); ++x) {
                        if ((*x) >= from) {
                                reached = true;
                        }
-                       
+
                        if (reached && (*x) > from) {
                                return *x;
                        }
@@ -1586,7 +1896,7 @@ Playlist::find_next_transient (nframes64_t from, int dir)
                        if ((*x) <= from) {
                                reached = true;
                        }
-                       
+
                        if (reached && (*x) < from) {
                                return *x;
                        }
@@ -1597,11 +1907,11 @@ Playlist::find_next_transient (nframes64_t from, int dir)
 }
 
 boost::shared_ptr<Region>
-Playlist::find_next_region (nframes_t frame, RegionPoint point, int dir)
+Playlist::find_next_region (framepos_t frame, RegionPoint point, int dir)
 {
        RegionLock rlock (this);
        boost::shared_ptr<Region> ret;
-       nframes_t closest = max_frames;
+       framepos_t closest = max_frames;
 
        bool end_iter = false;
 
@@ -1609,9 +1919,9 @@ Playlist::find_next_region (nframes_t frame, RegionPoint point, int dir)
 
                if(end_iter) break;
 
-               nframes_t distance;
+               frameoffset_t distance;
                boost::shared_ptr<Region> r = (*i);
-               nframes_t pos = 0;
+               framepos_t pos = 0;
 
                switch (point) {
                case Start:
@@ -1640,7 +1950,7 @@ Playlist::find_next_region (nframes_t frame, RegionPoint point, int dir)
                        break;
 
                default: /* backwards */
-                       
+
                        if (pos < frame) {
                                if ((distance = frame - pos) < closest) {
                                        closest = distance;
@@ -1658,25 +1968,25 @@ Playlist::find_next_region (nframes_t frame, RegionPoint point, int dir)
        return ret;
 }
 
-nframes64_t
-Playlist::find_next_region_boundary (nframes64_t frame, int dir)
+framepos_t
+Playlist::find_next_region_boundary (framepos_t frame, int dir)
 {
        RegionLock rlock (this);
 
-       nframes64_t closest = max_frames;
-       nframes64_t ret = -1;
+       framepos_t closest = max_frames;
+       framepos_t ret = -1;
 
        if (dir > 0) {
 
                for (RegionList::iterator i = regions.begin(); i != regions.end(); ++i) {
 
                        boost::shared_ptr<Region> r = (*i);
-                       nframes64_t distance;
-                       
+                       frameoffset_t distance;
+
                        if (r->first_frame() > frame) {
 
                                distance = r->first_frame() - frame;
-                               
+
                                if (distance < closest) {
                                        ret = r->first_frame();
                                        closest = distance;
@@ -1684,9 +1994,9 @@ Playlist::find_next_region_boundary (nframes64_t frame, int dir)
                        }
 
                        if (r->last_frame () > frame) {
-                               
+
                                distance = r->last_frame () - frame;
-                               
+
                                if (distance < closest) {
                                        ret = r->last_frame ();
                                        closest = distance;
@@ -1697,14 +2007,14 @@ Playlist::find_next_region_boundary (nframes64_t frame, int dir)
        } else {
 
                for (RegionList::reverse_iterator i = regions.rbegin(); i != regions.rend(); ++i) {
-                       
+
                        boost::shared_ptr<Region> r = (*i);
-                       nframes64_t distance;
+                       frameoffset_t distance;
 
                        if (r->last_frame() < frame) {
 
                                distance = frame - r->last_frame();
-                               
+
                                if (distance < closest) {
                                        ret = r->last_frame();
                                        closest = distance;
@@ -1712,7 +2022,7 @@ Playlist::find_next_region_boundary (nframes64_t frame, int dir)
                        }
 
                        if (r->first_frame() < frame) {
-                               
+
                                distance = frame - r->first_frame();
 
                                if (distance < closest) {
@@ -1739,8 +2049,87 @@ Playlist::mark_session_dirty ()
        }
 }
 
+bool
+Playlist::set_property (const PropertyBase& prop)
+{
+        if (prop == Properties::regions.property_id) {
+                const RegionListProperty::ChangeRecord& change (dynamic_cast<const RegionListProperty*>(&prop)->change());
+                regions.update (change);
+                return (!change.added.empty() && !change.removed.empty());
+        }
+        return false;
+}
+
+void
+Playlist::rdiff (vector<StatefulDiffCommand*>& cmds) const
+{
+       RegionLock rlock (const_cast<Playlist *> (this));
+
+       for (RegionList::const_iterator i = regions.begin(); i != regions.end(); ++i) {
+               if ((*i)->changed ()) {
+                        StatefulDiffCommand* sdc = new StatefulDiffCommand (*i);
+                        cmds.push_back (sdc);
+                }
+       }
+}
+
+void
+Playlist::clear_owned_history ()
+{
+       RegionLock rlock (this);
+
+       for (RegionList::iterator i = regions.begin(); i != regions.end(); ++i) {
+                (*i)->clear_history ();
+        }
+}
+
+void
+Playlist::update (const RegionListProperty::ChangeRecord& change)
+{
+        DEBUG_TRACE (DEBUG::Properties, string_compose ("Playlist %1 updates from a change record with %2 adds %3 removes\n", 
+                                                        name(), change.added.size(), change.removed.size()));
+        
+        freeze ();
+        /* add the added regions */
+        for (RegionListProperty::ChangeContainer::iterator i = change.added.begin(); i != change.added.end(); ++i) {
+                add_region ((*i), (*i)->position());
+        }
+        /* remove the removed regions */
+        for (RegionListProperty::ChangeContainer::iterator i = change.removed.begin(); i != change.removed.end(); ++i) {
+                remove_region (*i);
+        }
+
+        thaw ();
+}
+
+PropertyList*
+Playlist::property_factory (const XMLNode& history_node) const
+{
+        const XMLNodeList& children (history_node.children());
+        PropertyList* prop_list = 0;
+
+        for (XMLNodeList::const_iterator i = children.begin(); i != children.end(); ++i) {
+
+                if ((*i)->name() == capitalize (regions.property_name())) {
+                        
+                        RegionListProperty* rlp = new RegionListProperty (*const_cast<Playlist*> (this));
+
+                        if (rlp->load_history_state (**i)) {
+                                if (!prop_list) {
+                                        prop_list = new PropertyList();
+                                }
+                                prop_list->add (rlp);
+                        } else {
+                                delete rlp;
+                        }
+                }
+        }
+
+        return prop_list;
+}
+
 int
-Playlist::set_state (const XMLNode& node)
+Playlist::set_state (const XMLNode& node, int version)
 {
        XMLNode *child;
        XMLNodeList nlist;
@@ -1765,24 +2154,27 @@ Playlist::set_state (const XMLNode& node)
        for (piter = plist.begin(); piter != plist.end(); ++piter) {
 
                prop = *piter;
-               
+
                if (prop->name() == X_("name")) {
                        _name = prop->value();
+                        _set_sort_id ();
+               } else if (prop->name() == X_("id")) {
+                        _id = prop->value();
                } else if (prop->name() == X_("orig_diskstream_id")) {
                        _orig_diskstream_id = prop->value ();
                } else if (prop->name() == X_("frozen")) {
-                       _frozen = (prop->value() == X_("yes"));
+                       _frozen = string_is_affirmative (prop->value());
                }
        }
 
-       clear (false);
-       
+       clear (true);
+
        nlist = node.children();
 
        for (niter = nlist.begin(); niter != nlist.end(); ++niter) {
 
                child = *niter;
-               
+
                if (child->name() == "Region") {
 
                        if ((prop = child->property ("id")) == 0) {
@@ -1791,41 +2183,42 @@ Playlist::set_state (const XMLNode& node)
                        }
                        
                        ID id = prop->value ();
-                       
+
                        if ((region = region_by_id (id))) {
 
-                               Change what_changed = Change (0);
+                               region->suspend_property_changes ();
 
-                               if (region->set_live_state (*child, what_changed, true)) {
-                                       error << _("Playlist: cannot reset region state from XML") << endmsg;
+                               if (region->set_state (*child, version)) {
+                                       region->resume_property_changes ();
                                        continue;
                                }
-
-                       } else if ((region = RegionFactory::create (_session, *child, true)) == 0) {
+                               
+                       } else if ((region = RegionFactory::create (_session, *child, true)) != 0) {
+                               region->suspend_property_changes ();
+                       } else {
                                error << _("Playlist: cannot create region from XML") << endmsg;
                                continue;
                        }
-
+                        
                        add_region (region, region->position(), 1.0);
 
                        // So that layer_op ordering doesn't get screwed up
                        region->set_last_layer_op( region->layer());
-
-               }                       
+                       region->resume_property_changes ();
+               }
        }
-       
-       notify_modified ();
 
-       thaw ();
-
-       /* update dependents, which was not done during add_region_internal 
-          due to in_set_state being true 
+       /* update dependents, which was not done during add_region_internal
+          due to in_set_state being true
        */
 
        for (RegionList::iterator r = regions.begin(); r != regions.end(); ++r) {
                check_dependents (*r, false);
        }
 
+       thaw ();
+       notify_contents_changed ();
+
        in_set_state--;
        first_set_state = false;
        return 0;
@@ -1834,21 +2227,24 @@ Playlist::set_state (const XMLNode& node)
 XMLNode&
 Playlist::get_state()
 {
-       return state(true);
+       return state (true);
 }
 
 XMLNode&
 Playlist::get_template()
 {
-       return state(false);
+       return state (false);
 }
 
+/** @param full_state true to include regions in the returned state, otherwise false.
+ */
 XMLNode&
 Playlist::state (bool full_state)
 {
        XMLNode *node = new XMLNode (X_("Playlist"));
        char buf[64];
-       
+
+       node->add_property (X_("id"), id().to_s());
        node->add_property (X_("name"), _name);
        node->add_property (X_("type"), _type.to_string());
 
@@ -1884,19 +2280,19 @@ Playlist::n_regions() const
        return regions.size();
 }
 
-nframes_t
+framecnt_t
 Playlist::get_maximum_extent () const
 {
        RegionLock rlock (const_cast<Playlist *>(this), false);
        return _get_maximum_extent ();
 }
 
-ARDOUR::nframes_t
+framecnt_t
 Playlist::_get_maximum_extent () const
 {
        RegionList::const_iterator i;
-       nframes_t max_extent = 0;
-       nframes_t end = 0;
+       framecnt_t max_extent = 0;
+       framepos_t end = 0;
 
        for (i = regions.begin(); i != regions.end(); ++i) {
                if ((end = (*i)->position() + (*i)->length()) > max_extent) {
@@ -1907,14 +2303,14 @@ Playlist::_get_maximum_extent () const
        return max_extent;
 }
 
-string 
+string
 Playlist::bump_name (string name, Session &session)
 {
        string newname = name;
 
        do {
                newname = bump_name_once (newname);
-       } while (session.playlist_by_name (newname)!=NULL);
+       } while (session.playlists->by_name (newname)!=NULL);
 
        return newname;
 }
@@ -1923,7 +2319,7 @@ Playlist::bump_name (string name, Session &session)
 layer_t
 Playlist::top_layer() const
 {
-       RegionLock rlock (const_cast<Playlist *> (this));       
+       RegionLock rlock (const_cast<Playlist *> (this));
        layer_t top = 0;
 
        for (RegionList::const_iterator i = regions.begin(); i != regions.end(); ++i) {
@@ -1945,79 +2341,120 @@ Playlist::set_edit_mode (EditMode mode)
 void
 Playlist::relayer ()
 {
-       /* don't send multiple Modified notifications
-          when multiple regions are relayered.
-       */
-       freeze ();
+        /* never compute layers when changing state for undo/redo or setting from XML*/
+
+        if (in_update || in_set_state) {
+                return;
+        }
+
+       bool changed = false;
+
+       /* Build up a new list of regions on each layer, stored in a set of lists
+          each of which represent some period of time on some layer.  The idea
+          is to avoid having to search the entire region list to establish whether
+          each region overlaps another */
+
+       /* how many pieces to divide this playlist's time up into */
+       int const divisions = 512;
+
+       /* find the start and end positions of the regions on this playlist */
+       framepos_t start = UINT_MAX;
+       framepos_t end = 0;
+       for (RegionList::const_iterator i = regions.begin(); i != regions.end(); ++i) {
+               start = min (start, (*i)->position());
+               end = max (end, (*i)->position() + (*i)->length());
+       }
 
-       /* build up a new list of regions on each layer */
+       /* hence the size of each time division */
+       double const division_size = (end - start) / double (divisions);
 
-       std::vector<RegionList> layers;
+       vector<vector<RegionList> > layers;
+       layers.push_back (vector<RegionList> (divisions));
 
        /* we want to go through regions from desired lowest to desired highest layer,
           which depends on the layer model
        */
 
-       RegionList copy = regions;
+       RegionList copy = regions.rlist();
+
+       /* sort according to the model and the layering mode that we're in */
+
+       if (_explicit_relayering) {
+
+               copy.sort (RegionSortByLayerWithPending ());
 
-       /* sort according to the model */
+       } else if (_session.config.get_layer_model() == MoveAddHigher || _session.config.get_layer_model() == AddHigher) {
+
+               copy.sort (RegionSortByLastLayerOp ());
 
-       if (_session.config.get_layer_model() == MoveAddHigher || _session.config.get_layer_model() == AddHigher) {
-               RegionSortByLastLayerOp cmp;
-               copy.sort (cmp);
        }
-       
+
+
        for (RegionList::iterator i = copy.begin(); i != copy.end(); ++i) {
 
+               /* reset the pending explicit relayer flag for every region, now that we're relayering */
+               (*i)->set_pending_explicit_relayer (false);
+
+               /* find the time divisions that this region covers */
+               int const start_division = floor ( ((*i)->position() - start) / division_size);
+               int end_division = floor ( ((*i)->position() + (*i)->length() - start) / division_size );
+               if (end_division == divisions) {
+                       end_division--;
+               }
+
+               assert (end_division < divisions);
+
                /* find the lowest layer that this region can go on */
                size_t j = layers.size();
                while (j > 0) {
                        /* try layer j - 1; it can go on if it overlaps no other region
                           that is already on that layer
                        */
-                       RegionList::iterator k = layers[j - 1].begin();
-                       while (k != layers[j - 1].end()) {
-                               if ((*k)->overlap_equivalent (*i)) {
+
+                       bool overlap = false;
+                       for (int k = start_division; k <= end_division; ++k) {
+                               RegionList::iterator l = layers[j-1][k].begin ();
+                               while (l != layers[j-1][k].end()) {
+                                       if ((*l)->overlap_equivalent (*i)) {
+                                               overlap = true;
+                                               break;
+                                       }
+                                       l++;
+                               }
+
+                               if (overlap) {
                                        break;
                                }
-                               k++;
                        }
 
-                       if (k != layers[j - 1].end()) {
-                               /* no overlap, so we can use this layer */
+                       if (overlap) {
+                               /* overlap, so we must use layer j */
                                break;
                        }
-                                       
-                       j--;
+
+                       --j;
                }
 
                if (j == layers.size()) {
                        /* we need a new layer for this region */
-                       layers.push_back (RegionList ());
+                       layers.push_back (vector<RegionList> (divisions));
                }
 
-               layers[j].push_back (*i);
-       }
-
-       /* first pass: set up the layer numbers in the regions */
-       for (size_t j = 0; j < layers.size(); ++j) {
-               for (RegionList::iterator i = layers[j].begin(); i != layers[j].end(); ++i) {
-                       (*i)->set_layer (j);
+               /* put a reference to this region in each of the divisions that it exists in */
+               for (int k = start_division; k <= end_division; ++k) {
+                       layers[j][k].push_back (*i);
+               }
+               
+               if ((*i)->layer() != j) {
+                       changed = true;
                }
-       }
-
-       /* sending Modified means that various kinds of layering
-          models operate correctly at the GUI
-          level. slightly inefficient, but only slightly.
-
-          We force a Modified signal here in case no layers actually
-          changed.
-       */
 
-       notify_modified ();
+               (*i)->set_layer (j);
+       }
 
-       thaw ();
+       if (changed) {
+               notify_layering_changed ();
+       }
 }
 
 /* XXX these layer functions are all deprecated */
@@ -2077,23 +2514,24 @@ Playlist::move_region_to_layer (layer_t target_layer, boost::shared_ptr<Region>
        RegionList::iterator i;
        typedef pair<boost::shared_ptr<Region>,layer_t> LayerInfo;
        list<LayerInfo> layerinfo;
-       layer_t dest;
 
        {
                RegionLock rlock (const_cast<Playlist *> (this));
-               
+
                for (i = regions.begin(); i != regions.end(); ++i) {
-                       
+
                        if (region == *i) {
                                continue;
                        }
 
+                       layer_t dest;
+
                        if (dir > 0) {
 
                                /* region is moving up, move all regions on intermediate layers
                                   down 1
                                */
-                               
+
                                if ((*i)->layer() > region->layer() && (*i)->layer() <= target_layer) {
                                        dest = (*i)->layer() - 1;
                                } else {
@@ -2115,12 +2553,12 @@ Playlist::move_region_to_layer (layer_t target_layer, boost::shared_ptr<Region>
                        }
 
                        LayerInfo newpair;
-                       
+
                        newpair.first = *i;
                        newpair.second = dest;
-                       
+
                        layerinfo.push_back (newpair);
-               } 
+               }
        }
 
        /* now reset the layers without holding the region lock */
@@ -2137,29 +2575,30 @@ Playlist::move_region_to_layer (layer_t target_layer, boost::shared_ptr<Region>
        for (list<LayerInfo>::iterator x = layerinfo.begin(); x != layerinfo.end(); ++x) {
                check_dependents (x->first, false);
        }
-       
+
        check_dependents (region, false);
 #endif
-       
+
        return 0;
 }
 
 void
-Playlist::nudge_after (nframes_t start, nframes_t distance, bool forwards)
+Playlist::nudge_after (framepos_t start, framecnt_t distance, bool forwards)
 {
        RegionList::iterator i;
-       nframes_t new_pos;
        bool moved = false;
 
        _nudging = true;
 
        {
                RegionLock rlock (const_cast<Playlist *> (this));
-               
+
                for (i = regions.begin(); i != regions.end(); ++i) {
 
                        if ((*i)->position() >= start) {
 
+                               framepos_t new_pos;
+
                                if (forwards) {
 
                                        if ((*i)->last_frame() > max_frames - distance) {
@@ -2167,9 +2606,9 @@ Playlist::nudge_after (nframes_t start, nframes_t distance, bool forwards)
                                        } else {
                                                new_pos = (*i)->position() + distance;
                                        }
-                                       
+
                                } else {
-                                       
+
                                        if ((*i)->position() > distance) {
                                                new_pos = (*i)->position() - distance;
                                        } else {
@@ -2207,7 +2646,7 @@ Playlist::find_region (const ID& id) const
 }
 
 boost::shared_ptr<Region>
-Playlist::region_by_id (ID id)
+Playlist::region_by_id (const ID& id)
 {
        /* searches all regions ever added to this playlist */
 
@@ -2218,7 +2657,7 @@ Playlist::region_by_id (ID id)
        }
        return boost::shared_ptr<Region> ();
 }
-       
+
 void
 Playlist::dump () const
 {
@@ -2230,9 +2669,9 @@ Playlist::dump () const
 
        for (RegionList::const_iterator i = regions.begin(); i != regions.end(); ++i) {
                r = *i;
-               cerr << "  " << r->name() << " [" 
-                    << r->start() << "+" << r->length() 
-                    << "] at " 
+               cerr << "  " << r->name() << " ["
+                    << r->start() << "+" << r->length()
+                    << "] at "
                     << r->position()
                     << " on layer "
                     << r->layer ()
@@ -2259,7 +2698,6 @@ void
 Playlist::shuffle (boost::shared_ptr<Region> region, int dir)
 {
        bool moved = false;
-       nframes_t new_pos;
 
        if (region->locked()) {
                return;
@@ -2269,13 +2707,13 @@ Playlist::shuffle (boost::shared_ptr<Region> region, int dir)
 
        {
                RegionLock rlock (const_cast<Playlist*> (this));
-               
-               
+
+
                if (dir > 0) {
-                       
+
                        RegionList::iterator next;
 
-                       for (RegionList::iterator i = regions.begin(); i != regions.end(); ++i) {       
+                       for (RegionList::iterator i = regions.begin(); i != regions.end(); ++i) {
                                if ((*i) == region) {
                                        next = i;
                                        ++next;
@@ -2286,6 +2724,8 @@ Playlist::shuffle (boost::shared_ptr<Region> region, int dir)
                                                        break;
                                                }
 
+                                               framepos_t new_pos;
+
                                                if ((*next)->position() != region->last_frame() + 1) {
                                                        /* they didn't used to touch, so after shuffle,
                                                           just have them swap positions.
@@ -2315,10 +2755,10 @@ Playlist::shuffle (boost::shared_ptr<Region> region, int dir)
                                }
                        }
                } else {
-                       
+
                        RegionList::iterator prev = regions.end();
-                       
-                       for (RegionList::iterator i = regions.begin(); i != regions.end(); prev = i, ++i) {     
+
+                       for (RegionList::iterator i = regions.begin(); i != regions.end(); prev = i, ++i) {
                                if ((*i) == region) {
 
                                        if (prev != regions.end()) {
@@ -2327,6 +2767,7 @@ Playlist::shuffle (boost::shared_ptr<Region> region, int dir)
                                                        break;
                                                }
 
+                                               framepos_t new_pos;
                                                if (region->position() != (*prev)->last_frame() + 1) {
                                                        /* they didn't used to touch, so after shuffle,
                                                           just have them swap positions.
@@ -2342,7 +2783,7 @@ Playlist::shuffle (boost::shared_ptr<Region> region, int dir)
 
                                                region->set_position ((*prev)->position(), this);
                                                (*prev)->set_position (new_pos, this);
-                                               
+
                                                /* avoid a full sort */
 
                                                regions.erase (i); // remove region
@@ -2363,17 +2804,17 @@ Playlist::shuffle (boost::shared_ptr<Region> region, int dir)
 
                relayer ();
                check_dependents (region, false);
-               
-               notify_modified();
+
+               notify_contents_changed();
        }
 
 }
 
 bool
-Playlist::region_is_shuffle_constrained (boost::shared_ptr<Region>) 
+Playlist::region_is_shuffle_constrained (boost::shared_ptr<Region>)
 {
        RegionLock rlock (const_cast<Playlist*> (this));
-       
+
        if (regions.size() > 1) {
                return true;
        }
@@ -2385,11 +2826,11 @@ void
 Playlist::update_after_tempo_map_change ()
 {
        RegionLock rlock (const_cast<Playlist*> (this));
-       RegionList copy (regions);
+       RegionList copy (regions.rlist());
 
        freeze ();
-       
-       for (RegionList::iterator i = copy.begin(); i != copy.end(); ++i) {     
+
+       for (RegionList::iterator i = copy.begin(); i != copy.end(); ++i) {
                (*i)->update_position_after_tempo_map_change ();
        }
 
@@ -2397,7 +2838,7 @@ Playlist::update_after_tempo_map_change ()
 }
 
 void
-Playlist::foreach_region (sigc::slot<void, boost::shared_ptr<Region> > s)
+Playlist::foreach_region (boost::function<void(boost::shared_ptr<Region>)> s)
 {
        RegionLock rl (this, false);
        for (RegionList::iterator i = regions.begin(); i != regions.end(); ++i) {
@@ -2405,4 +2846,38 @@ Playlist::foreach_region (sigc::slot<void, boost::shared_ptr<Region> > s)
        }
 }
 
+void
+Playlist::set_explicit_relayering (bool e)
+{
+       if (e == false && _explicit_relayering == true) {
+
+               /* We are changing from explicit to implicit relayering; layering may have been changed whilst
+                  we were in explicit mode, and we don't want that to be undone next time an implicit relayer
+                  occurs.  Hence now we'll set up region last_layer_op values so that an implicit relayer
+                  at this point would keep regions on the same layers.
+
+                  From then on in, it's just you and your towel.
+               */
+
+               RegionLock rl (this);
+               for (RegionList::iterator i = regions.begin(); i != regions.end(); ++i) {
+                       (*i)->set_last_layer_op ((*i)->layer ());
+               }
+       }
+
+       _explicit_relayering = e;
+}
+
+
+bool
+Playlist::has_region_at (framepos_t const p) const
+{
+       RegionLock (const_cast<Playlist *> (this));
        
+       RegionList::const_iterator i = regions.begin ();
+       while (i != regions.end() && !(*i)->covers (p)) {
+               ++i;
+       }
+
+       return (i != regions.end());
+}