Fix crash when re-assigning groups to a disjunct set.

[ardour.git] / gtk2_ardour / group_tabs.cc

diff --git a/gtk2_ardour/group_tabs.cc b/gtk2_ardour/group_tabs.cc
index 303f4abac7926baae370ff3d414ab9d065a1d537..4c17064e769efe445738987270774ff1f938b475 100644 (file)
--- a/gtk2_ardour/group_tabs.cc
+++ b/gtk2_ardour/group_tabs.cc
@@ -212,7 +212,15 @@ GroupTabs::on_button_release_event (GdkEventButton*)
                                run_new_group_dialog (&routes, false);
                        } else {
                                boost::shared_ptr<RouteList> r = _session->get_routes ();
-                               for (RouteList::iterator i = r->begin(); i != r->end(); ++i) {
+                               /* First add new ones, then remove old ones.
+                                * We cannot allow the group to become temporarily empty, because
+                                * Session::route_removed_from_route_group() will delete empty groups.
+                                */
+                               for (RouteList::const_iterator i = routes.begin(); i != routes.end(); ++i) {
+                                       /* RouteGroup::add () ignores routes already present in the set */
+                                       _dragging->group->add (*i);
+                               }
+                               for (RouteList::const_iterator i = r->begin(); i != r->end(); ++i) {
 
                                        bool const was_in_tab = find (
                                                _initial_dragging_routes.begin(), _initial_dragging_routes.end(), *i
@@ -222,10 +230,9 @@ GroupTabs::on_button_release_event (GdkEventButton*)
 
                                        if (was_in_tab && !now_in_tab) {
                                                _dragging->group->remove (*i);
-                                       } else if (!was_in_tab && now_in_tab) {
-                                               _dragging->group->add (*i);
                                        }
                                }
+
                        }
                }