swallow all events in pianoroll automation group if there's no active automation

gtk2_ardour/pianoroll_midi_view.cc

@@ -104,6 +104,7 @@ PianorollMidiView::PianorollMidiView (std::shared_ptr<ARDOUR::MidiTrack> mt,
 	_note_group->raise_to_top ();
 
 	automation_group = new ArdourCanvas::Rectangle (&parent);
+	automation_group->Event.connect (sigc::mem_fun (*this, &PianorollMidiView::automation_group_event));
 	CANVAS_DEBUG_NAME (automation_group, "cue automation group");
 	automation_group->set_fill_color (UIConfiguration::instance().color ("midi automation track fill"));
 	automation_group->set_data ("linemerger", this);
@@ -118,6 +119,16 @@ PianorollMidiView::~PianorollMidiView ()
 	delete velocity_display;
 }
 
+bool
+PianorollMidiView::automation_group_event (GdkEvent* ev)
+{
+	if (!active_automation) {
+		/* Eat the event to prevent the parent seeing it */
+		return true;
+	}
+	return false;
+}
+
 bool
 PianorollMidiView::midi_canvas_group_event (GdkEvent* ev)
 {

gtk2_ardour/pianoroll_midi_view.h

@@ -146,6 +146,7 @@ class PianorollMidiView : public MidiView
 	void unset_active_automation ();
 
 	bool midi_canvas_group_event (GdkEvent*);
+	bool automation_group_event (GdkEvent*);
 	Gtkmm2ext::Color line_color_for (Evoral::Parameter const &);
 
 	void reset_width_dependent_items (double pixel_width);