Window geometry?

[Chris Quinn <cq htec demon co uk>]

I've got a window that appears when the cursor moves over an icon, and which disappears when the cursor leaves the area covered by it. I catch LEAVE_NOTIFY events but unfortunately this seems to include movement *into* buttons populating the window
ie. if the cursor is on a blank part of the window then moves into the area of a button. I tried catching such signals for each of the buttons but had no joy (maybe I should have used the 'after' versions?). 
I thought a simpler solution would be to find the geometry of the window and just check against cursor position.
But, improbably, I have not found an interface function or structure yielding this info.

Any ideas?

PS. the mail archive of this list does not contain the word geometry!! This also seems improbable!