docs: def brush( self ):
          """
          Return the main brush for this node.
          
          :return     <QBrush>
          """
          # create the background brush
          grad = QLinearGradient()
          rect = self.rect()
          
          grad.setStart(QPointF(0, rect.y()))
          grad.setFinalStop(QPointF(0, rect.bottom()))
          
          grad.setColorAt(0, self.baseColor())
          grad.setColorAt(1, self.alternateColor())
              
          return QBrush(grad)