Specifies whether @widget has a #GdkWindow of its own. Note that
all realized widgets have a non-%NULL “window” pointer
(gtk_widget_get_window() 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.
Specifies whether @widget has a #GdkWindow of its own. Note that all realized widgets have a non-%NULL “window” pointer (gtk_widget_get_window() 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.