Problems with selection region drawing on Qt4

Hello!

I need to draw a rectangle on the QGLWidget for selection by region on the OCC 3D Viewer. The problem is: when I drawing the rectangle using QPainter, I see the white backgrount of the parent Widget. In the Qt3 such problems was not appeared. At the OCC Qt3 samples they using the simple QWidget with some additional flags. But this did not work on Qt4, only QGLWidget can be resised properly on Dt4. Who knows, how to solve this problem?
My code is:

Q3VBox* vb = new Q3VBox( this);
vb->setFrameStyle( QFrame::StyledPanel | QFrame::Sunken );
myView = new View(vb);

..............

View::View(QWidget* parent) : QGLWidget( parent)
{
int windowHandle = (int) winId();
short hi, lo;
lo = (short) windowHandle;
hi = (short) (windowHandle >> 16);
Handle(WNT_Window) hWnd = new WNT_Window(Handle(Graphic3d_WNTGraphicDevice)::DownCast(myContext->CurrentViewer()->Device()),(int) hi,(int) lo);
myView->SetWindow( hWnd );
..........
}

void View::DrawRectangle(const int MinX, const int MinY, const int MaxX, const int MaxY)
{
QPainter thePainter(this);
thePainter.setPen(Qt::white);
QRect aRect;
aRect.setRect( MinX, MinY, Maxx, Maxy);
thePainter.drawRect(aRect);
}