[Xcb] Getting time since server started and `XIfEvent'

[Vincent Torri]

>
> When using both Xlib and XCB on the same connection, only one library
> can own the event queue. By default it's Xlib. If you access XCB's event
> queue when Xlib owns it, the results are entirely uncertain;

ooooooh, maybe it's the reason why I have problems when I run an XCB app
(the problems with the events, if you remember)

Vincent