When a window is created and destroyed on the TCL/TK side, MFC never seems
to 'hear' about it. That is, MFC dispatches events for a window that has
been destroyed by TCL/TK. If compiled with debug, this causes the entire
application to halt with debug box (you know that abort, retry, cancel
thing). The reason that it halts is that wincore.cpp has some asserts that
fire if it is sees a bad window handle. I confirmed this by using SPY++ and
stepping through the code to make sure.
Thanks,
Mark F. Sanderson