gdk-window-frame-extents (window)

window -- a toplevel gdk-window object

rect -- a gdk-rectangle with bounding box of the window frame

Obtains the bounding box of the window, including window manager titlebar/borders if any. The frame position is given in root window coordinates. To get the position of the window itself, rather than the frame, in root window coordinates, use the function gdk-window-origin.