Comment 54 for bug 220628

Ding ding ding!

Breakpoint 2, xcb_generate_id (c=0x1450640) at xcb_xid.c:51
51 c->xid.last = range->start_id;
$559 = {response_type = 1 '\001', pad0 = 0 '\0', sequence = 29345, length = 0, start_id = 41385235, count = 1}

Breakpoint 1, gdk_x_error (display=0x144fc00, error=0x7ffff91140d0) at /build/buildd/gtk+2.0-2.14.4/gdk/x11/gdkmain-x11.c:613

I finally caught the crash in action, and indeed, it occurred immediately after the first time the X server sent back a xid_range_reply with count=1.

So my crashes are definitely due to this xcb bug.