static QWidget *qwtBGWidget( QWidget *widget )
{
    QWidget *w = widget;

    for ( ; w->parentWidget() != NULL; w = w->parentWidget() )
    {
        if ( w->autoFillBackground() || 
            w->testAttribute( Qt::WA_StyledBackground ) )
        {
            return w;
        }
    }

    return w;
}
void QwtPlotAbstractCanvas::drawUnstyled( QPainter *painter )
{
    fillBackground( painter );

    QWidget *w = canvasWidget();

    if ( w->autoFillBackground() )
    {
        const QRect canvasRect = w->rect();

        painter->save();

        painter->setPen( Qt::NoPen );
        painter->setBrush( w->palette().brush( w->backgroundRole() ) );

        const QRect frameRect = w->property( "frameRect" ).toRect();
        if ( borderRadius() > 0.0 && ( canvasRect == frameRect ) )
        {
            const int frameWidth = w->property( "frameWidth" ).toInt();
            if ( frameWidth > 0 )
            {
                painter->setClipPath( borderPath2( canvasRect ) );
                painter->drawRect( canvasRect );
            }
            else
            {
                painter->setRenderHint( QPainter::Antialiasing, true );
                painter->drawPath( borderPath2( canvasRect ) );
            }
        }
        else
        {
            painter->drawRect( canvasRect );
        }

        painter->restore();
    }

    drawCanvas( painter );
}