Dragging windows together

[Andrew Shafer <shafer realmsys com>]

Are there GTK or GDK level functions what will let me drag two top level
windows together?

I have two toplevel windows without decorations and I want to be able to
drag them using a grip on one so they maintain the same relative
position.

I'm looking at doing it building up XEvents, but I'd really like to do
it with a higher level API if possible.

If anyone has any ideas, please respond. . .