I want the Audio button to bring up the list of available audio
tracks when first pressed (no switch yet), and cyclically switch
through the audio tracks for every following press. After a timeout
(5 seconds), or if any other key is pressed, the list will disappear.
At first I also thought using Up/Down to move the cursor through the
list would be a good idea, but that causes trouble in case the list
just disappeared when pressing Up or Down, which then results in a
channel switch. Maybe once Up/Down is pressed, the timeout should
be increased to the normal menu timeout (2 minutes) and an Ok press
made necessary to actually switch the track.