Frame (MenuBar) corrupt inside Windows app

[Grinchman]

Hello.
I build Qt application as DLL. That dll is used in Windows app (3ds max 2012). To make my Qt app as child window for 3ds max I do:

void MainWindow::setParentWindowHandle(fVoid *parent)
{
	if(parent) 
	{	
		SetParent(winId(), (HWND)parent);	
 
		QEvent e(QEvent::EmbeddingControl);
		QApplication::sendEvent(this, &e);
	}
}

void MainWindow::setParentWindowHandle(fVoid *parent)
{
	if(parent) 
	{	
		SetParent(winId(), (HWND)parent);	

		QEvent e(QEvent::EmbeddingControl);
		QApplication::sendEvent(this, &e);
	}
}

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But, when my window is showed, border frame(menu bar with close, maximize buttons) isn't painted, it's corrupt (or something like this, see the image below).
Frameless.jpg

But close, maximize buttons is there! I may click them.

Don't know why it isn't painted...

P.S.: When my app isn't child of 3ds max then all frames, buttons are showed fine