Trigger the audio selection change logic when switching timing controllers

Results in the display seeking to the active line when audio is opened
(if seeking to active line is enabled), and initializes the scrollbar
properly.

Updates #1732.

src/audio_display.cpp

@@ -1232,6 +1232,7 @@ void AudioDisplay::OnTimingController()
 
 		OnStyleRangesChanged();
 		OnMarkerMoved();
+		OnSelectionChanged();
 	}
 }