Very slow window refresh

["Georgios Kapetanakis" <georgios cs york ac uk>]

Hi,

I've recently started writing a gtk+ application in Linux and I've come
across a very strange behaviour. I have created 4 toplevel windows, one of
which displays an image colour histogram, and another two that display live
video in two different ways from a frame grabber board. These 3 windows are
updated continuously using a gtk timeout function called every 40ms. The
video input is captured in a separate POSIX thread continuously. The fourth
window is a control window, which consists of simple gtk widgets (toolbar
with pixmaps, menu, slider controls, labels, etc.).

The problem I'm facing is that the fourth window (the control window)
refreshes extremely slowly, whereas the rest are operating normally. When
another window clips even a small area of the control window, then it takes
about 30secs for the control window to refresh and become operational again.
However, if I click somewhere on the window (say a toolbar button) while
it's refreshing, when it becomes fully operational again it remembers the
button click and executes the specified action.

I'm not familiar with the internals of gtk, so if someone can provide some
help and advice on what is going wrong, it will be most appreciated.

/G