Jonas Dreßler authored Dec 11, 2020 and Marge Bot committed Dec 11, 2020

Apparently it can happen that a timeline tries to pick a frame clock
from an actor that's on a stage, but the actor still doesn't find a
frame clock and returns NULL.

This probably is the case when starting a timeline right after attaching
an actor to a newly created stage, so before the first stage-update
cycle. In this case clutter_actor_update_stage_views() will not have run
and the stage-actor will have priv->stage_views set to NULL even though
there are stage views.

To prevent this from happening, use the complete list of stage views
maintained by the backend when picking a frame clock for the stage.

This doesn't fix any issue appearing on master, but is correct
nonetheless.

Part-of: <!1631>