[qt5] repainting qwidget

[zodiac]

Hello.

void dUpload::show( Qt::WindowFlags flags )
{
	//setWindowFlags( flags );
 
	setAttribute(Qt::WA_NoSystemBackground, true);
 
	show();
}

void dUpload::show( Qt::WindowFlags flags )
{
	//setWindowFlags( flags );

	setAttribute(Qt::WA_NoSystemBackground, true);

	show();
}

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After call setAttribute function from this code my qwidget doesn't repaint (i.e. I see artefacts from child widgets), but when I resize that widget, then it repaints.

Is it bug in qt5 or I do something wrong?

OS: win7 + msvs 2010.