docs: def mouseMoveEvent(self, event):
          """
          Drags the selection view for this widget.
          
          :param      event | <QMouseMoveEvent>
          """
          w = event.pos().x() - self._region.x()
          h = event.pos().y() - self._region.y()
          
          self._region.setWidth(w)
          self._region.setHeight(h)
          self.repaint()
          
          super(XSnapshotWidget, self).mouseMoveEvent(event)