on_expose_event not being called when expected

["Garth's KidStuff" <garthskidstuff gmail com>]

Hey All,

I have a large application whose drawing logic is based on the clock example
(http://www.gtkmm.org/docs/gtkmm-2.4/docs/tutorial/html/ch15s07.html) in the
documentation:

* When objects need to be redrawn they set a rectangle
* A timer fires every so often (100ms in my case), and I call
invalidate_rect  with the above rectangle
* My Gtk::DrawingArea-derived class overrides on_expose_event and draws the
objects

This logic works impeccably (*grin*) until the CPU is under heavy load.  In
that case, I can see the invalidate_rect calls happening but on_expose_event
doesn't get called until the cpu load is back to normal.  I've been banging
my head against this for a few days now and would love some new ideas about
how to attack the problem.

Thanks in advance.

-- 
Garth Upshaw
Garth's KidStuff