Override Qt method

def paintEvent(self, event):
        """Override Qt method"""
        painter = QPainter(self)
        size = self.size()

        color = QColor(self.color)
        color.setAlphaF(.5)
        painter.setPen(color)

        for column in self.columns:
            x = self.editor.fontMetrics().width(column * '9')
            painter.drawLine(x, 0, x, size.height())