Gtk app partly white when brought to the foreground from behind a window, any thoughts why?

[Antony Stace <antony claire co jp>]

Hi Folks

I have an application(app.x) which I want to make a little better.  If
functions fine except it has the annoying property that if I put part of
the application behind another window and the click the toolbar on app.x
to bring it to the foreground the application comes to the foreground
but the part which was behind the window is all white for a brief
instance of time.  If I run other applications like xclock, xcalc,
netscape, etc this does not happen.  The application consists of a few
gtk drawing areas(about 4 inches high and 2 inches wide(not sure if this
would be classed as a large drawing area)) which remain unchanged for
most of the time so they are not being update.
Is there anything anyone can think of that might be causing this
behaviour?

Cheers

Antony