Sets a focus chain, overriding the one computed automatically by GTK+.
In principle each widget in the chain should be a descendant of the container, but this is not enforced by this method, since it's allowed to set the focus chain before you pack the widgets, or have a widget in the chain that isn't always packed. The necessary checks are done when the focus chain is actually traversed.
See also: get_focus_chain() , unset_focus_chain()