[Xcb] How to wake up the GUI thread in XCB?

[Cosmin Apreutesei]

> Qt has the same problem and it solves it by causing an event to be generated

That worked perfectly, thanks. It also solved my need for an async
"quit" function trivially.

I have another question, this time I'm not sure I can get away without
threads. I would need something like xcb_wait_for_event(timeout). It
would make implementing timers trivial. But I guess
xcb_wait_for_event() doesn't use select() internally on a NULL
connection, so it's not as simple as just exposing the timeout arg
from that, right? Is that why I don't find an API for that, or is it
more complicated than that?

Thanks again for the help.