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 "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.
Since 2.18
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 "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. Since 2.18