Sending messages to windows on other threads can deadlock if those threads
aren't processing messages. The deeper issue is that we shouldn't be touching
the window styles in the first place, but avoiding that may not be feasible
without specific support from winex11/winemac.
Signed-off-by: Henri Verbeet <hverbeet@codeweavers.com>
Signed-off-by: Alexandre Julliard <julliard@winehq.org>