Fixed the bug that menus appear at the wrong place by reading the ICCCM.
Fixed the bug that menus appear at the wrong place by reading the
ICCCM.

Trick is that the top-level sheet's parent window is not the root
window but the window manager's decoration, so genuine configure
notify events state the real window's position and not the position
relative to the root window origin.

onixie/mcclim,slyrus/mcclim,antifuchs/mcclim,antifuchs/mcclim,swflint/McCLIM,slyrus/mcclim,onixie/mcclim,onixie/mcclim,swflint/McCLIM,swflint/McCLIM