Whenever some area of the window is invalidated (directly in the
window or in a child window) this gets called with region in
the coordinate space of window. You can use region to just
keep track of the dirty region, or you can actually change
region in case you are doing display tricks like showing
a child in multiple places.
Whenever some area of the window is invalidated (directly in the window or in a child window) this gets called with
regionin the coordinate space ofwindow. You can useregionto just keep track of the dirty region, or you can actually changeregionin case you are doing display tricks like showing a child in multiple places.