gdk-window-position (window)

window -- a gdk-window object

x -- a :int with the x coordinate of window
y -- a :int with the y coordinate of window

Obtains the position of the window as reported in the most-recently-processed gdk-event-configure event. Contrast with the function gdk-window-geometry which queries the X server for the current window position, regardless of which events have been received or processed. The position coordinates are relative to the window's parent window.