GtkHandleBox::set_snap_edge
Sets the edge which must be aligned to reattach the float window. When
edge on both the float window and the ghost widget
are aligned the float window will be reattached to its original window.
If the snap edge is not explicitly set using set_snap_edge() , the snap edge will be
determined automatically by the placement of the handle.
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 the snap
edge does not move when the handlebox is deattached. For instance, if the
handlebox is packed at the bottom of a GtkVBox, 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 GTK_POS_BOTTOM.
See also: set_handle_position()