The mouse filter needs to lock RootLayer, but the event dispatcher lock is held
during that time, too, so that the focus cannot change in the mean time.
On the other side, ServerWindow needs to lock the event dispatcher when adding
or removing a listener, or for AS_GET_MOUSE - but since it always helds the
root layer lock during message dispatching this easily resulted in a deadlock.
git-svn-id: file:///srv/svn/repos/haiku/haiku/trunk@15146 a95241bf-73f2-0310-859d-f6bbb57e9c96
85d981378a