Convert MIDI region transparency when loading old sessions

libs/ardour/midi_playlist.cc

@@ -340,7 +340,6 @@ MidiPlaylist::render (MidiChannelFilter* filter)
 
 	bool all_transparent = true;
 
-#ifndef MIXBUS // XXX Mixbus 8 always has transparent MIDI regions (until session is converted in v9)
 	/* skip bottom-most region, transparency is irrelevant */
 	for (auto i = ++regs.begin(); i != regs.end(); ++i) {
 		if ((*i)->opaque ()) {
@@ -348,7 +347,6 @@ MidiPlaylist::render (MidiChannelFilter* filter)
 			break;
 		}
 	}
-#endif
 
 	Evoral::EventList<samplepos_t> evlist;
 

libs/ardour/midi_region.cc

@@ -357,10 +357,7 @@ MidiRegion::set_state (const XMLNode& node, int version)
 {
 	int ret = Region::set_state (node, version);
 
-#ifdef MIXBUS
-#warning remember to convert MidiRegion opacity for v9 /* see also MidiPlaylist::render */
-#endif
-	if (version < 7000) {
+	if (version < 7001) {
 		/* previous sessions had uncontionally transparent MIDI regions */
 		override_opaqueness (false);
 	}