void QGWidget::painEvent(QPaintEvent *event)
{
QPainter painter(this);
painter.setRenderHint(QPainter::Antialiasing,true);

int side=qMin(width(),height());
painter.setViewport((width()-side)/2,(height()-side)/2,side,side);

painter.setWindow(0,0,50,50);
draw(&painter);
}

void QGWidget::draw(QPainter *painter)
{
QPen thickPen(palette().foreground(),1.5);
painter->setPen(thickPen);

QRadialGradient haloGradient(0,0,20,0,0);
haloGradient.setColorAt(0.0,Qt::lightGray);
haloGradient.setColorAt(0.8,Qt::darkGray);
haloGradient.setColorAt(0.9,Qt::white);
haloGradient.setColorAt(1.0,Qt::black);

painter->setBrush(haloGradient);
painter->drawRect(1,1,50,50);

painter->setPen(thickPen);
painter->drawText(0,25,"Label");

}