gdk:window-effective-toplevel (window)

window -- a gdk:window object

The effective gdk:window toplevel containing window.

Gets the toplevel window that is an ancestor of window. Works like the gdk:window-toplevel function, but treats an offscreen window's embedder as its parent, using the gdk:window-effective-parent function.

See also the gdk:offscreen-window-embedder function.