Merge pull request #6070 from riadvice/fix-lock-for-late-joiners

...tton-client/src/org/bigbluebutton/main/events/BBBEvent.as

.../src/org/bigbluebutton/main/maps/ApplicationEventMap.mxml

...ent/src/org/bigbluebutton/main/model/users/UserService.as

...rc/org/bigbluebutton/main/views/MainApplicationShell.mxml

...rg/bigbluebutton/modules/layout/managers/LayoutManager.as

.../org/bigbluebutton/modules/layout/views/LayoutsCombo.mxml