The "Allow Midi files to Play" menu option flips
a switch used by the OnAssertPlayMIDIFile method;
this method is used to prevent playing MIDI files.
(This could be due to lack of audio hardware or
to avoid degrading performance.)
 
(Note: Assert methods normally are used to abort
all further processing of an action, while the
Handle Methods modify the processing. These
two methods can each be overridden in code by
direct assignment for Assert types and virtual
overriding for Handle types.)



