The failure is an assertion being hit in libxcb rather than a segfault, which implies that the library isn't bugged itself but rather it's catching a fault higher up in the system.
The xcb assertion code is: if (XLIB_SEQUENCE_COMPARE(event_sequence, >, dpy->request)) { throw_thread_fail_assert("Unknown sequence " "number while " "processing queue", xcb_xlib_threads_sequence_lost); There is a big warning in the comments above this code: /* Thread-safety rules: * * At most one thread can be reading from XCB's event queue at a time. * If you are not the current event-reading thread and you need to find * out if an event is available, you must wait. * * The same rule applies for reading replies. * * A single thread cannot be both the the event-reading and the * reply-reading thread at the same time. * * We always look at both the current event and the first pending reply * to decide which to process next. * * We always process all responses in sequence-number order, which may * mean waiting for another thread (either the event_waiter or the * reply_waiter) to handle an earlier response before we can process or * return a later one. If so, we wait on the corresponding condition * variable for that thread to process the response and wake us up. */ -- You received this bug notification because you are a member of Ubuntu-X, which is subscribed to libx11 in Ubuntu. https://bugs.launchpad.net/bugs/901675 Title: apport-gtk assert failure: python: ../../src/xcb_io.c:273: poll_for_event: Assertion `!xcb_xlib_threads_sequence_lost' failed. To manage notifications about this bug go to: https://bugs.launchpad.net/ubuntu/+source/apport/+bug/901675/+subscriptions _______________________________________________ Mailing list: https://launchpad.net/~ubuntu-x-swat Post to : ubuntu-x-swat@lists.launchpad.net Unsubscribe : https://launchpad.net/~ubuntu-x-swat More help : https://help.launchpad.net/ListHelp