'Adjust the handle to the remembered position.
This is done only once.'

def exposed(self, area, event):

    altoancho = self.window.get_size()[self.dimension]
    newpos = (altoancho // 2)
    self.set_position(newpos)
    self.winconfig[self.widgname] = newpos
    self.disconnect(self.signal)
    return True
