Windows: Crash after calling DestroyWindow on a manually created window parented on a QWidget's hwnd.

1)Create a new window by Win32API (CreateWindowEx)
2)After destroy the window by DestroyWindow, Qt App will be crashed:

qwindowsd.dll!QWindowsWindow::testFlag(unsigned int f=8192) line 258 + 0xa byte C++
qwindowsd.dll!QWindowsContext::windowsProc(HWND__ * hwnd=0x000c09d4, unsigned int message=2, QtWindows::WindowsEventType et=DestroyEvent, unsigned int wParam=0, long lParam=0, long * result=0x0026c560) line 798 + 0xd byte C++
qwindowsd.dll!qWindowsWndProc(HWND__ * hwnd=0x000c09d4, unsigned int message=2, unsigned int wParam=0, long lParam=0) line 1097 + 0x24 byte C++

because of null pointer access at
qt-everywhere-opensource-src-5.3.0\qtbase\src\plugins\platforms\windows\qwindowscontext.cpp
line 798
if (!platformWindow->testFlag(QWindowsWindow::WithinDestroy)) {

which code was added by Qt5.2.0.
So Qt5.1.1 was no problem.