==20416== Thread 1:
==20416== not a condition variable: cond 0xffefff530
==20416==    at 0x4C34F97: pthread_cond_destroy@* (in /usr/lib/valgrind/vgpreload_drd-amd64-linux.so)
==20416==    by 0x6415449: ??? (in /usr/lib/x86_64-linux-gnu/libxcb.so.1.1.0)
==20416==    by 0x6415511: xcb_wait_for_reply (in /usr/lib/x86_64-linux-gnu/libxcb.so.1.1.0)
==20416==    by 0x51E948E: _XReply (in /usr/lib/x86_64-linux-gnu/libX11.so.6.3.0)
==20416==    by 0x51DF923: XQueryExtension (in /usr/lib/x86_64-linux-gnu/libX11.so.6.3.0)
==20416==    by 0x51D3BE1: XInitExtension (in /usr/lib/x86_64-linux-gnu/libX11.so.6.3.0)
==20416==    by 0x523BFA3: XkbUseExtension (in /usr/lib/x86_64-linux-gnu/libX11.so.6.3.0)
==20416==    by 0x51DA2B2: XOpenDisplay (in /usr/lib/x86_64-linux-gnu/libX11.so.6.3.0)