A container with just one child

The Bin 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 Bin, including Window, Button, Frame, HandleBox, and ScrolledWindow.

 | GObject
 | +----Object
 | +----Widget
 | +----Container
 | +----Bin
 | +----Window
 | +----Alignment
 | +----Frame
 | +----Button
 | +----Item
 | +----ComboBox
 | +----EventBox
 | +----Expander
 | +----HandleBox
 | +----ToolItem
 | +----ScrolledWindow
 | +----Viewport