[gtkada] Double expose event

[manuel.op.de.coul at eon-benelux.com]

I hope somebody has dealt with this before:
I have some dialogs with a GtkDrawingArea that has
a callback handler for expose_event. This works
fine when a window in front of it is removed, then
the drawing area gets redrawn by the callback.
However when the window containing the drawing area
is resized, resizing the drawing area with it,
there are two expose_events and consequently two
redraws. Happens both on Unix and Windows.
How to prevent this? I'm not looking for double buffering.
Thanks,

Manuel