GtkBin a container with just one child. The #GtkBin widget is a container with just one child. It is not very useful itself, but it is useful for deriving subclasses, since it provides common code needed for handling a single child widget. Many GTK+ widgets are subclasses of #GtkBin, including #GtkWindow, #GtkButton, #GtkFrame, #GtkHandleBox, and #GtkScrolledWindow. The #GtkBin-struct struct contains the following fields. (These fields should be considered read-only. They should never be set by an application.) #GtkWidget *child; the child widget.