Widget.setHasWindow

Specifies whether widget has a #GdkWindow of its own. Note that all realized widgets have a non-null “window” pointer ([gtk.widget.Widget.getWindow] never returns a null window when a widget is realized), but for many of them it’s actually the #GdkWindow of one of its parent widgets. Widgets that do not create a window for themselves in #GtkWidget::realize must announce this by calling this function with has_window = false.

This function should only be called by widget implementations, and they should call it in their init() function.