widget has a GdkWindow of its own. Note that
all realized widgets have a non-NULL "window" pointer
(gtkWidgetGetWindow 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 create a window for
themselves in GtkWidget::realize() however must announce this by
calling this function with has.window = TRUE.gtkWidgetSetHasWindow(object, has.window)objecthas.windowwidget has a window.init() function.
Since 2.18