Some actor implementation might avoid imposing any layout on their
children. The Actor base class usually assumes some sort of layout
management is in place, so it will queue relayouts when, for instance,
an actor is shown or is hidden. If the parent of the actor does not
impose any layout, though, showing or hiding one of its children will
not affect the layout of the others.
An example of this kind of container is ClutterGroup.
By adding a new Actor flag, CLUTTER_ACTOR_NO_LAYOUT, and by making
the Group actor set it on itself, the Actor base class can now decide
whether or not to queue a relayout. The flag is not meant to be used
by application code, and should only be set when implementing a new
container.
http://bugzilla.openedhand.com/show_bug.cgi?id=1838
c4f27b1556