QGestureManager crash

This bugtrace was generated from running Scribus 1.5.1svn using Qt5.4.2 on OSX 10.10.3
First reported downstream (Scribus Bugtracker):
http://bugs.scribus.net/view.php?id=13150

Possible related bugs Qt bugs:
https://bugreports.qt.io/browse/QTBUG-46264
https://bugreports.qt.io/browse/QTBUG-20946

Screencast of bug triggered in Scribus:
https://www.dropbox.com/s/n6eyr4z9r2cwu1s/Crash_bug.m4v?dl=0

Bugtrace:
Process 23890 stopped

• thread #1: tid = 0x17924, 0x00000001049c3461 QtWidgets`QGestureManager::filterEvent(QWidget*, QEvent*) + 481, queue = 'com.apple.main-thread', stop reason = EXC_BAD_ACCESS (code=1, address=0x34)
  frame #0: 0x00000001049c3461 QtWidgets`QGestureManager::filterEvent(QWidget*, QEvent*) + 481
  QtWidgets`QGestureManager::filterEvent:
  -> 0x1049c3461 <+481>: movq 0x8(%rbx), %rax
  0x1049c3465 <+485>: movq 0x1a8(%rax), %r15
  0x1049c346c <+492>: cmpq $0x0, 0x10(%r15)
  0x1049c3471 <+497>: je 0x1049c3600 ; <+896>
  (lldb) bt
• thread #1: tid = 0x17924, 0x00000001049c3461 QtWidgets`QGestureManager::filterEvent(QWidget*, QEvent*) + 481, queue = 'com.apple.main-thread', stop reason = EXC_BAD_ACCESS (code=1, address=0x34)
• frame #0: 0x00000001049c3461 QtWidgets`QGestureManager::filterEvent(QWidget*, QEvent*) + 481
  frame #1: 0x0000000104971c81 QtWidgets`QApplication::notify(QObject*, QEvent*) + 465
  frame #2: 0x0000000105e20253 QtCore`QCoreApplication::notifyInternal(QObject*, QEvent*) + 115
  frame #3: 0x00000001049c262e QtWidgets`QGestureManager::deliverEvents(QSet<QGesture*> const&, QSet<QGesture*>*) + 2542
  frame #4: 0x00000001049c1399 QtWidgets`QGestureManager::filterEventThroughContexts(QMultiMap<QObject*, Qt::GestureType> const&, QEvent*) + 4249
  frame #5: 0x00000001049c3626 QtWidgets`QGestureManager::filterEvent(QWidget*, QEvent*) + 934
  frame #6: 0x0000000104971c81 QtWidgets`QApplication::notify(QObject*, QEvent*) + 465
  frame #7: 0x0000000105e20253 QtCore`QCoreApplication::notifyInternal(QObject*, QEvent*) + 115
  frame #8: 0x00000001049762fa QtWidgets`QApplicationPrivate::translateRawTouchEvent(QWidget*, QTouchDevice*, QList<QTouchEvent::TouchPoint> const&, unsigned long) + 3290
  frame #9: 0x00000001049cacd9 QtWidgets`QWidgetWindow::event(QEvent*) + 489
  frame #10: 0x0000000104970713 QtWidgets`QApplicationPrivate::notify_helper(QObject*, QEvent*) + 307
  frame #11: 0x0000000104973b15 QtWidgets`QApplication::notify(QObject*, QEvent*) + 8293
  frame #12: 0x0000000105e20253 QtCore`QCoreApplication::notifyInternal(QObject*, QEvent*) + 115
  frame #13: 0x0000000105029416 QtGui`QGuiApplicationPrivate::processTouchEvent(QWindowSystemInterfacePrivate::TouchEvent*) + 5622
  frame #14: 0x00000001050134ba QtGui`QWindowSystemInterface::sendWindowSystemEvents(QFlags<QEventLoop::ProcessEventsFlag>) + 346
  frame #15: 0x0000000108baa941 libqcocoa.dylib`QCocoaEventDispatcherPrivate::postedEventsSourceCallback(void*) + 33
  frame #16: 0x00007fff96328a01 CoreFoundation`_CFRUNLOOP_IS_CALLING_OUT_TO_A_SOURCE0_PERFORM_FUNCTION_ + 17
  frame #17: 0x00007fff9631ab8d CoreFoundation`__CFRunLoopDoSources0 + 269
  frame #18: 0x00007fff9631a1bf CoreFoundation`__CFRunLoopRun + 927
  frame #19: 0x00007fff96319bd8 CoreFoundation`CFRunLoopRunSpecific + 296
  frame #20: 0x00007fff9c8d156f HIToolbox`RunCurrentEventLoopInMode + 235
  frame #21: 0x00007fff9c8d11ee HIToolbox`ReceiveNextEventCommon + 179
  frame #22: 0x00007fff9c8d112b HIToolbox`_BlockUntilNextEventMatchingListInModeWithFilter + 71
  frame #23: 0x00007fff9490f9bb AppKit`_DPSNextEvent + 978
  frame #24: 0x00007fff9490ef68 AppKit`-[NSApplication nextEventMatchingMask:untilDate:inMode:dequeue:] + 346
  frame #25: 0x00007fff94904bf3 AppKit`-[NSApplication run] + 594
  frame #26: 0x0000000108ba989a libqcocoa.dylib`QCocoaEventDispatcher::processEvents(QFlags<QEventLoop::ProcessEventsFlag>) + 2266
  frame #27: 0x0000000105e1da3c QtCore`QEventLoop::exec(QFlags<QEventLoop::ProcessEventsFlag>) + 396
  frame #28: 0x0000000105e207fa QtCore`QCoreApplication::exec() + 346
  frame #29: 0x00000001007d3ee9 Scribus`mainApp(int, char**) + 90
  frame #30: 0x00007fff9bbb55c9 libdyld.dylib`start + 1
  frame #31: 0x00007fff9bbb55c9 libdyld.dylib`start + 1