elisp, mouse-tracking: gracefully NOT handling events

["David Vanderschel" <DJV4@Austin.RR.com>]

I have a program in which I am using track-mouse.  It
turns out that mouse events are not the only events
you can get in a track-mouse loop.  My program is not
prepared to handle all of them.  (I don't know how
many other potential event types there are in this
context, but I am sure that I do not want to learn how
to properly treat all of them.)  In the face of an
event my program does not understand, it can and does
abort its current operation with no difficulty.
(Indeed, that is a normal sort of occurrence for other
reasons as well.)  However, it may be that such an
unrecognized event could occur, the event is
significant, and failure to deal with it could be
harmful to the 'system'.  It seems to me that I need a
system function to call when I don't know what to do
with an event.  The idea is, "Take this event.  I did not
know what to do with it, so please do with it
whatever you would have done with it had I not been in
a track-mouse loop."  Is there such a function?
(Failing that, it seems like there ought to be a way
to tell the system which types of events you are
prepared to handle in a track-mouse loop so you won't
get events you don't understand.)

Regards,
  David V.