gtk:widget-toplevel (widget)

widget -- a gtk:widget object

The topmost ancestor of widget, or widget itself if there is no ancestor.

This function returns the topmost widget in the container hierarchy the widget is a part of. If the widget has no parent widgets, it will be returned as the topmost widget.

Note the difference in behavior versus the gtk:widget-ancestor function. The call (gtk:widget-ancestor widget "GtkWindow") would return nil if the widget was not inside a toplevel window, and if the window was inside a gtk:window derived widget which was in turn inside the toplevel gtk:window widget. While the second case may seem unlikely, it actually happens when a gtk:plug widget is embedded inside a gtk:socket widget within the same application.

To reliably find the toplevel gtk:window widget, use the gtk:widget-toplevel function and check the type of the result to be of "GtkWindow" type. For instance, to get the title of the toplevel window of the widget, one might use:

(defun get-widget-toplevel-title (widget)
  (let ((toplevel (gtk:widget-toplevel widget)))
    (when (eq (gtype "GtkWindow") (g:type-from-instance toplevel))
      (gtk:window-title toplevel))))