code: def resizeEvent(self, event):
          
          self.setUpdatesEnabled(False)
          super(XPopupWidget, self).resizeEvent(event)
          
          self.adjustMask()
          self.setUpdatesEnabled(True)
          
          x = self.width() - self._sizeGrip.width()
          y = self.height() - self._sizeGrip.height()
          
          self._leftSizeGrip.move(0, y)
          self._sizeGrip.move(x, y)
docs: Resizes this widget and updates the mask.
          
          :param      event | <QResizeEvent>