cut buffer must not mess around with libardour selection

Fixes range mode selection/cut/copy that would previously clear track selection

gtk2_ardour/editor.cc

@@ -390,8 +390,8 @@ Editor::Editor ()
 	, _visible_track_count (-1)
 	,  toolbar_selection_clock_table (2,3)
 	,  automation_mode_button (_("mode"))
-	, selection (new Selection (this))
-	, cut_buffer (new Selection (this))
+	, selection (new Selection (this, true))
+	, cut_buffer (new Selection (this, false))
 	, _selection_memento (new SelectionMemento())
 	, _all_region_actions_sensitized (false)
 	, _ignore_region_action (false)

gtk2_ardour/selection.cc

@@ -57,10 +57,11 @@ struct AudioRangeComparator {
 	}
 };
 
-Selection::Selection (const PublicEditor* e)
+Selection::Selection (const PublicEditor* e, bool mls)
 	: tracks (e)
 	, editor (e)
 	, next_time_id (0)
+	, manage_libardour_selection (mls)
 {
 	clear ();
 
@@ -1544,6 +1545,10 @@ Selection::set (const TrackViewList& track_list)
 void
 Selection::clear_tracks (bool)
 {
+	if (!manage_libardour_selection) {
+		return;
+	}
+
 	Session* s = editor->session();
 	if (s) {
 		CoreSelection& selection (s->selection());

gtk2_ardour/selection.h

@@ -90,7 +90,7 @@ class Selection : public sigc::trackable, public PBD::ScopedConnectionList
 	/** only used when this class is used as a cut buffer */
 	MidiNoteSelection    midi_notes;
 
-	Selection (PublicEditor const * e);
+	Selection (PublicEditor const * e, bool manage_libardour_selection);
 
 	// Selection& operator= (const Selection& other);
 
@@ -230,6 +230,7 @@ class Selection : public sigc::trackable, public PBD::ScopedConnectionList
   private:
 	PublicEditor const * editor;
 	uint32_t next_time_id;
+	bool     manage_libardour_selection;
 
 	TrackViewList add_grouped_tracks (TrackViewList const & t);
 };