midi_region_view: use absolute_time_to_region_beats

* this fixes the location of the 'ghost note' that is shown
 when adding notes with the Draw tool

gtk2_ardour/midi_region_view.cc

@@ -4094,7 +4094,8 @@ MidiRegionView::update_ghost_note (double x, double y, uint32_t state)
 	samplepos_t const unsnapped_sample = editor.pixel_to_sample (global_x);
 	Temporal::timepos_t snapped_pos = timepos_t (unsnapped_sample);
 	editor.snap_to (snapped_pos, RoundDownAlways, SnapToGrid_Scaled);
-	const Temporal::Beats snapped_beats = _region->position().distance (snapped_pos).beats ();
+
+	const Temporal::Beats snapped_beats = _region->absolute_time_to_region_beats(snapped_pos);
 
 	/* prevent Percussive mode from displaying a ghost hit at region end */
 	if ((midi_view()->note_mode() == Percussive) && (snapped_beats >= _region->length().beats())) {

libs/ardour/ardour/region.h

@@ -303,7 +303,7 @@ public:
 	Temporal::Beats absolute_time_to_source_beats(Temporal::timepos_t const &) const;
 
 	Temporal::Beats absolute_time_to_region_beats (Temporal::timepos_t const & b) const {
-		return position().distance (b).beats ();
+		return position().distance (b+start()).beats ();
 	}
 
 	int apply (Filter &, Progress* progress = 0);