Application crashes within qt-sources after deleting QGraphicsView on OSX

Hello. My application crashes within qt-sources.
I've already asked question about this problem: http://stackoverflow.com/questions/30476905/qt-application-crashes-on-notifyinternalreceiver-event-in-osx-10-10-2 but I know more information now.

I added debug code in qt-sources and understood:

Application crashes in qtimerinfo_unix_p.cpp: QTimerInfoList::activateTimers()

I understood that function tries to activate timer on wrong qt-object pointer (already deleted):

Timer. Id: 8 Interval: 300
TimerInfo ptr: 0x7fde9d5662b0
Programm Crashes

I've reimplemented QApplication::notify and understood, that

TimerInfo ptr: 0x7fde9d5662b0

registered by QGraphicsView::viewport():

-- Timer Registered --
Timer. Id: 8 Interval: 300
TimerInfo ptr: 0x7fde9d5662b0
TimerInfo obj: QWidget(0x7fde9a7940a0, name = "ViewViewportBad")
TimerInfo obj parent: QGraphicsView(0x7fde9a7a44c0, name = "EditController view")
--  --

But why qt-object is incorrect?
Until crash I found next notify:

Parent ptr: QGraphicsView(0x7fde9a7a44c0, name = "EditController view") Object name: "EditController view"
Receiver ptr: QWidget(0x7fde9a7940a0, name = "ViewViewportBad") Object name: "ViewViewportBad"
Event ptr: QWidget(0x7fde9a7940a0, name = "ViewViewportBad") Type: 16

It means that viewport already deleted (Qevent::type 16 = "Destroy"). (I trying to delete QGraphicsView in destructor of my class)

What timers registered viewport?
Why timers didn't deleted after destroying viewport?
Ho to fix this bug?

PS: application crashes every 5-10 runs