'Push the current view limits and position onto the stack.'

def push_current(self):

    views = []
    pos = []
    for a in self.canvas.figure.get_axes():
        views.append(a._get_view())
        pos.append((a.get_position(True).frozen(), a.get_position().frozen()))
    self._views.push(views)
    self._positions.push(pos)
    self.set_history_buttons()
