'Drag a link\'s endpoint to another node.'

def dragNetLink(self, event):

    if (self.link is None):
        return
    x = self.canvasx(event.x_root)
    y = self.canvasy(event.y_root)
    c = self.canvas
    c.coords(self.link, self.linkx, self.linky, x, y)
