Picture-in-Picture not working with dom.w3c_pointer_events.enabled=false

Picture-in-Picture for videos does not work (at least in Firefox 75, probably since 71) with pref dom.w3c_pointer_events.enabled = false. We might be able to set it to true in legacy/trac#28729 (moved), so we should check that. But perhaps it's worth filing a bug in bugzilla in any case, since it looks like an internal Firefox UI should not be broken because of dom.w3c_pointer_events.enabled being set to false.