gtk sunlight crashes in background with [xcb] error

gtk sunlight crashes - but leaves the last displayed image.. running from the command line gives:

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PING www.google.com (216.58.208.36) 56(84) bytes of data.
64 bytes from lhr08s07-in-f36.1e100.net (216.58.208.36): icmp_seq=1 ttl=53 time=23.8 ms

--- www.google.com ping statistics ---
1 packets transmitted, 1 received, 0% packet loss, time 0ms
rtt min/avg/max/mdev = 23.867/23.867/23.867/0.000 ms
  % Total % Received % Xferd Average Speed Time Time Time Current
                                 Dload Upload Total Spent Left Speed
100 147k 100 147k 0 0 180k 0 --:--:-- --:--:-- --:--:-- 180k
[xcb] Unknown request in queue while dequeuing
[xcb] Most likely this is a multi-threaded client and XInitThreads has not been called
[xcb] Aborting, sorry about that.
gtk-sunlight: ../../src/xcb_io.c:179: dequeue_pending_request: Assertion `!xcb_xlib_unknown_req_in_deq' failed.
Aborted (core dumped)
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I'm running:

Linux 3.19.0-28-generic #30-Ubuntu SMP Mon Aug 31 15:52:51 UTC 2015 x86_64 x86_64 x86_64 GNU/Linux

Let me know if you need more info

Max