gdk_set_back_pixmap and GtkDrawingArea

[Maciej Stachowiak <mstachow mit edu>]

I'm trying to make a drawing area widget update faster by setting my
backing pixmap as its background pixmap, by using gdk_set_back_pixmap
on the widget's window field. However, this has two problems. First,
the pixmap is not drawn in the background initially; the background is
just set to an apparently random color from the pixmap. However,
dragging another window over my app exposes the pixmap. Second, when I
draw something to the pixmap, it does not get updated, again until I
drag another window over it so it gets exposure events. Am I totally
misunderstanding how background pixmaps are supposed to work?

 - Maciej Stachowiak