d624db18c5
Previously we had various things watching for notify::mapped so we could be more lazy about updating non-visible actors, but it was fairly ad-hoc. The deferred work system unifies these callbacks, and also adds a timeout so that we don't delay changes arbitrarily; this way we avoid a storm of work if you stay out of the overview for a while, then go in. https://bugzilla.gnome.org/show_bug.cgi?id=603522