due to the see-through nature of the title bar and our standard black
window background, the title bar appears dark grey opposed to the
expected light grey.
we change the window background to white but at the same time set the
background of the enclosed view to black. that way the title bar has a
white background and the background of our video stays black in all
cases. this prevents white flashing in some cases when the video is
resized with too heavy render settings.
After removing synchronous libdispatch calls, this looks like it doesn't
deadlock anymore. I also experimented with pthread_mutex_trylock liek wm4
suggested, but it leads to some annoying black flickering. I will fallback to
that only if some new deadlocks are discovered.
