The HandleBox widget allows a portion of a window to be "torn off". It is a Gtk.Bin widget that displays its child with a handle that the user can drag to create a separate floating window containing the child widget and the 'handle'.

A thin ghost is drawn in the original location of the HandleBox. By dragging the separate window back to its original location, it can be reattached. When reattaching, the ghost and float window, must be aligned along one of the edges, the HandlBox.SnapEdge. This can either be specified by the application programmer explicitly, otherwise a reasonable default will be used, based on the HandleBox.HandlePosition.

To make detaching and reattaching the HandleBox as minimally confusing as possible to the user, it is important to set the snap edge so that it does not move when the HandleBox is deattached. For instance, if the HandleBox is packed at the bottom of a Gtk.VBox, then when the HandleBox is detached, the bottom edge of the HandleBox's allocation will remain fixed as the height of the HandleBox shrinks, so the snap edge should be set to PositionType.Bottom.

The child of this widget is set using the Container.Add method in Gtk.Container.