Exception not handled in widgetlock()

Describe the issue

I want to use a selector matplotlib.widgets.RectangleSelector , it is incompatible with zoom and pan
So I try to call widget lock to prevent user from using zoom in the same time.

minimum code:

%matplotlib ipympl
import matplotlib.pyplot as plt
fig,ax = plt.subplots()
ax.plot([0,1],[0,1])
fig.canvas.widgetlock(ax)   # get the widget lock

if you then hit the zoom or pan matplotlib button, which also try to get the lock, you get

ValueError                                Traceback (most recent call last)
File ~/spike/venvOW/lib/python3.9/site-packages/ipympl/backend_nbagg.py:279, in Canvas._handle_message(self, object, content, buffers)
    276     self.manager.handle_json(content)
    278 else:
--> 279     self.manager.handle_json(content)

...

File ~/spike/venvOW/lib/python3.9/site-packages/matplotlib/widgets.py:42, in LockDraw.__call__(self, o)
     40 """Reserve the lock for *o*."""
     41 if not self.available(o):
---> 42     raise ValueError('already locked')
     43 self._owner = o

ValueError: already locked

Alternatively, I could use the right click for the selector, but I have not found a way to restrict zoom and pan to left click only.

Versions

 3.9.7 (default, Sep 16 2021, 13:09:58) 
[GCC 7.5.0]
ipympl version: 0.8.8
Selected Jupyter core packages...
IPython          : 8.0.1
ipykernel        : 6.9.1
ipywidgets       : 7.6.5
jupyter_client   : 7.1.2
jupyter_core     : 4.9.2
jupyter_server   : 1.13.5
jupyterlab       : not installed
nbclient         : 0.5.11
nbconvert        : 6.4.2
nbformat         : 5.1.3
notebook         : 6.4.8
qtconsole        : 5.2.2
traitlets        : 5.1.1

最小限の Jupyter 例で問題を再現し、その後、トレースバックに示されている widget lock の処理の周辺を ipympl/backend_nbagg.py と matplotlib/widgets.py で確認してください。zoom または pan が占有中の lock の取得を試みた場合に期待される動作を確認し、その操作によって未捕捉の ValueError が発生しなくなったことを示すカバレッジを追加してください。