I assume that this is happening because of the border around the window. The
border is pretty ugly (again, not present on OSX), but necessary in GTK
right now because that's how window resizing is done. I'd suggest that
instead, window resizing be done with an _invisible_ border (ideally with
the same default radius as the shadow in Compiz) and that the rendered
border be completely independent, and not present on maximized windows.
I assume that this is happening because of the border around the window. The
border is pretty ugly (again, not present on OSX), but necessary in GTK
right now because that's how window resizing is done. I'd suggest that
instead, window resizing be done with an _invisible_ border (ideally with
the same default radius as the shadow in Compiz) and that the rendered
border be completely independent, and not present on maximized windows.