subclassing code.
* clutter/win32/clutter-stage-win32.h:
* clutter/win32/clutter-stage-win32.c: Now inherits from
ClutterGroup and implements ClutterStageWindow instead of
inheriting directly from ClutterStage.
* clutter/win32/clutter-event-win32.c (message_translate): Now
takes an extra parameter to return whether DefWindowProc should be
called. This is needed to prevent the default WM_CLOSE handler
from destroying the window.
* clutter/win32/clutter-backend-win32.c
(clutter_backend_win32_dispose): Destroy all of the stages using
g_slist_foreach as per bug #871. Now also destroys the GL context.
(clutter_backend_win32_get_features): Added assertions to ensure
there is a valid GL context.
(clutter_backend_win32_ensure_context): Accepts NULL stage. Gets
implementation pointer from the stage.
0b8a500fca