ideas on how to use overlays with GTK/GDK ?

[Paul Barton-Davis <pbd Op Net>]

Adrian Nye's Xlib book has a nice explanation on the use of
XAllocColorCells() to do non-destructive overlays. I notice that gdk
has a function which calls this (gdk_colors_alloc()), but I'm having a
hard time convincing myself that I understand how to use the GDK color
allocation/use interface to do the same thing as Nye's example.

Could anyone point me to some source (maybe in the gimp ?) that does
this, so I can take a look ? I have my stuff working with XOR, but I
think that overlays would be a lot more useful for lots of reasons.

Oh, and Owen, the reason that Gnome_Canvas isn't the right thing is
that I'm actively redrawing the overlays as I move a mouse. I don't
get the impression that the GnomeCanvas model is really designed with
this in mind.

--p