timeline: fixed double remove on transitions

Fixes #1655

app/widget/timelinewidget/timelinewidget.cpp

@@ -447,7 +447,8 @@ void TimelineWidget::SplitAtPlayhead()
 
 void TimelineWidget::ReplaceBlocksWithGaps(const QVector<Block *> &blocks,
                                            bool remove_from_graph,
-                                           MultiUndoCommand *command)
+                                           MultiUndoCommand *command,
+                                           bool handle_transitions)
 {
   foreach (Block* b, blocks) {
     if (dynamic_cast<GapBlock*>(b)) {
@@ -458,7 +459,7 @@ void TimelineWidget::ReplaceBlocksWithGaps(const QVector<Block *> &blocks,
 
     Track* original_track = b->track();
 
-    command->add_child(new TrackReplaceBlockWithGapCommand(original_track, b));
+    command->add_child(new TrackReplaceBlockWithGapCommand(original_track, b, handle_transitions));
 
     if (remove_from_graph) {
       command->add_child(new NodeRemoveWithExclusiveDependenciesAndDisconnect(b));

app/widget/timelinewidget/timelinewidget.h

@@ -112,7 +112,7 @@ public:
 
   void RestoreSplitterState(const QByteArray& state);
 
-  static void ReplaceBlocksWithGaps(const QVector<Block *> &blocks, bool remove_from_graph, MultiUndoCommand *command);
+  static void ReplaceBlocksWithGaps(const QVector<Block *> &blocks, bool remove_from_graph, MultiUndoCommand *command, bool handle_transitions = true);
 
   /**
    * @brief Retrieve the QGraphicsItem at a particular scene position

app/widget/timelinewidget/tool/pointer.cpp

@@ -591,7 +591,7 @@ void PointerTool::FinishDrag(TimelineViewMouseEvent *event)
         blocks_to_delete[i] = blocks_moving.at(i).block;
       }
 
-      parent()->ReplaceBlocksWithGaps(blocks_to_delete, false, command);
+      parent()->ReplaceBlocksWithGaps(blocks_to_delete, false, command, false);
     }
 
     if (inserting) {

app/widget/timelinewidget/undo/timelineundogeneral.cpp

@@ -441,7 +441,7 @@ void TrackListInsertGaps::undo()
 void TrackReplaceBlockWithGapCommand::redo()
 {
   // Determine if this block is connected to any transitions that should also be removed by this operation
-  if (transition_remove_commands_.isEmpty()) {
+  if (handle_transitions_ && transition_remove_commands_.isEmpty()) {
     CreateRemoveTransitionCommandIfNecessary(false);
     CreateRemoveTransitionCommandIfNecessary(true);
   }

app/widget/timelinewidget/undo/timelineundogeneral.h

@@ -196,12 +196,13 @@ private:
 
 class TrackReplaceBlockWithGapCommand : public UndoCommand {
 public:
-  TrackReplaceBlockWithGapCommand(Track* track, Block* block) :
+  TrackReplaceBlockWithGapCommand(Track* track, Block* block, bool handle_transitions = true) :
     track_(track),
     block_(block),
     existing_gap_(nullptr),
     existing_merged_gap_(nullptr),
     our_gap_(nullptr),
+    handle_transitions_(handle_transitions),
     position_command_(nullptr)
   {
   }
@@ -232,6 +233,8 @@ private:
   bool existing_gap_precedes_;
   GapBlock* our_gap_;
 
+  bool handle_transitions_;
+
   NodeSetPositionAsChildCommand* position_command_;
 
   QObject memory_manager_;