def boundingRect(self):
        if not self.source:  # or not self.dest:
            return QtCore.QRectF()
        penWidth = 1
        extra = (penWidth + self.arrowSize) / 2.0
        return QtCore.QRectF(self.sourcePoint,
                             QtCore.QSizeF(self.destPoint.x() - self.sourcePoint.x(),
                                           self.destPoint.y() - self.sourcePoint.y())).normalized().adjusted(-extra, -extra, extra, extra)
Hit box assistance.  Only let the user click on the tip of the line.
dataset/ETHPy150Open andrew-gardner/dependsworkflow/depends/depends_graphics_widgets.py/DrawEdge.boundingRect