Scale MIDI track vertical range to match widgest range of notes in child regions.

Fiddled with canvas theme a bit to make tempo more visible and probably annoy pure audio MIDI/tempo haters.
Fix track-specific-color display on mixer strips for MIDI tracks.


git-svn-id: svn://localhost/ardour2/trunk@2112 d708f5d6-7413-0410-9779-e7cbd77b26cf

gtk2_ardour/midi_time_axis.cc

@@ -128,6 +128,12 @@ MidiTimeAxisView::~MidiTimeAxisView ()
 {
 }
 
+MidiStreamView*
+MidiTimeAxisView::midi_view()
+{
+	return dynamic_cast<MidiStreamView*>(_view);
+}
+
 guint32
 MidiTimeAxisView::show_at (double y, int& nth, Gtk::VBox *parent)
 {