The only actor that results in a mix of the old Container API and the
new Actor API is ClutterStage. By inheritance, a Stage is a Group, but
we don't want it to behave like a Group - as it already overrides most
of the Actor API, and the reason why it was made as a Group in the
first place was convenience for adding/removing children.
Given that touching Group to make it aware of the new Actor API has
rapidly devolved into a struggle between a Demiurge that tries to
avoid breakage and a Chaos that finds new and interesting ways to
break ClutterGroup, let's declare API bankruptcy here and now.
ClutterStage should override ClutterContainer methods, and use the
layout management of ClutterFixedLayout as the proper class that it
was meant to be ages ago. Let ClutterGroup rot in pieces.
Now that we reinstated Group to its "former glory", we need to ensure
that applications using the deprecated containers with the new DOM API
in ClutterActor can actually work - or, at least, not break horribly.
This actually means making sure that ClutterStage and ClutterGroup can
cope with the DOM, while retaining their old implementations, as well as
their bizarre idiosyncrasies and their utter, utter brokenness.
Making Group just a proxy to Actor broke some behaviour that application
and toolkit code was relying on. Let's keep Group around to fight
another day.
This commit fixes gnome-shell as far as I can test it.
A Group is a just a ClutterActor with the layout-manager property set at
instance initialization time. It doesn't need anything else from
ClutterActor's vtable, except the slightly custom show_all/hide_all
implementation, and a simplified get_paint_volume.
The Group functionality is now provided by ClutterActor.
Sadly, we need to keep the ClutterGroup structure definition in the
non-deprecated header because ClutterStage inherits from Group - an API
wart that was never fixed during the 0.x cycles, and that we'll have to
keep around until we can break API.
