[Xcb] libxcb/libX11 deadlocking and asserting in multi-threaded use

[Nicholas Allen]

> By the way, you can always work around Xlib threading issues by using a
> mutex of your own to ensure that you never call Xlib from more than one
> thread at once. I'm told this was a common strategy even before
> Xlib/XCB.
How would I call XNextEvent in this case? XNextEvent will block while
still holding my mutex so all other threads will also block until an
event arrives.

Cheers,

Nick