Freeze in QXcbConnection

Qt Creator is freezing from time to time with this stack trace.

0 pthread_cond_wait@@GLIBC_2.3.2 pthread_cond_wait.S 185 0x7fce29885ca4
1 _xcb_conn_wait xcb_conn.c 368 0x7fce269a8ae6
2 wait_for_reply xcb_in.c 395 0x7fce269a9e57
3 xcb_wait_for_reply xcb_in.c 425 0x7fce269aa07b
4 QXcbConnection::sync qxcbconnection.cpp 1510 0x7fce23a35c4f
5 QXcbShmImage::preparePaint qxcbbackingstore.cpp 244 0x7fce23a5432d
6 QXcbBackingStore::beginPaint qxcbbackingstore.cpp 273 0x7fce23a544ea
7 QBackingStore::beginPaint qbackingstore.cpp 161 0x7fce2a532520
8 QWidgetBackingStore::beginPaint qwidgetbackingstore.cpp 313 0x7fce2af6900e
9 QWidgetBackingStore::sync qwidgetbackingstore.cpp 1052 0x7fce2af6cd6a
10 QWidgetPrivate::syncBackingStore qwidget.cpp 1680 0x7fce2af97c43
11 QWidget::event qwidget.cpp 8226 0x7fce2afa8b83
12 QMainWindow::event qmainwindow.cpp 1471 0x7fce2b11e151
13 QApplicationPrivate::notify_helper qapplication.cpp 3470 0x7fce2af5e6b4
14 QApplication::notify qapplication.cpp 3435 0x7fce2af5e50f
15 QCoreApplication::notifyInternal qcoreapplication.cpp 871 0x7fce29d95a18
16 QCoreApplication::sendEvent qcoreapplication.h 232 0x7fce29d99683
17 QCoreApplicationPrivate::sendPostedEvents qcoreapplication.cpp 1475 0x7fce29d96d2d
18 QCoreApplication::sendPostedEvents qcoreapplication.cpp 1333 0x7fce29d966bf
19 QGraphicsViewPrivate::dispatchPendingUpdateRequests qgraphicsview_p.h 202 0x7fce2b338919
20 QGraphicsScenePrivate::_q_emitUpdated qgraphicsscene.cpp 383 0x7fce2b31f546
21 QGraphicsScene::qt_static_metacall moc_qgraphicsscene.cpp 175 0x7fce2b337da1
22 QMetaCallEvent::placeMetaCall qobject.cpp 479 0x7fce29dd1553
23 QObject::event qobject.cpp 1078 0x7fce29dd2508
24 QGraphicsScene::event qgraphicsscene.cpp 3478 0x7fce2b32a068
25 QmlDesigner::FormEditorScene::event formeditorscene.cpp 351 0x7fcdf5aef532
26 QApplicationPrivate::notify_helper qapplication.cpp 3470 0x7fce2af5e6b4
27 QApplication::notify qapplication.cpp 2891 0x7fce2af5ba41
28 QCoreApplication::notifyInternal qcoreapplication.cpp 871 0x7fce29d95a18
29 QCoreApplication::sendEvent qcoreapplication.h 232 0x7fce29d99683
30 QCoreApplicationPrivate::sendPostedEvents qcoreapplication.cpp 1475 0x7fce29d96d2d
31 QCoreApplication::sendPostedEvents qcoreapplication.cpp 1333 0x7fce29d966bf
32 postEventSourceDispatch qeventdispatcher_glib.cpp 279 0x7fce29e0ccd3
33 g_main_context_dispatch /lib/x86_64-linux-gnu/libglib-2.0.so.0 0x7fce28863f05
34 ?? /lib/x86_64-linux-gnu/libglib-2.0.so.0 0x7fce28864248
35 g_main_context_iteration /lib/x86_64-linux-gnu/libglib-2.0.so.0 0x7fce28864304
36 QEventDispatcherGlib::processEvents qeventdispatcher_glib.cpp 426 0x7fce29e0d4a9
37 QPAEventDispatcherGlib::processEvents qeventdispatcher_glib.cpp 123 0x7fce23a67be6
38 QEventLoop::processEvents qeventloop.cpp 136 0x7fce29d9262a
39 QEventLoop::exec qeventloop.cpp 212 0x7fce29d928ff
40 QCoreApplication::exec qcoreapplication.cpp 1124 0x7fce29d960ed
41 QGuiApplication::exec qguiapplication.cpp 1328 0x7fce2a38b07a
42 QApplication::exec qapplication.cpp 2695 0x7fce2af5b2e3
43 main main.cpp 530 0x40e73f