Spurious warning calling fig.show() in jupyter inline backend

[dstansby]

Bug report

Bug summary

Using fig.show() in a notebook raises what seems like an un-needed warning. After calling plt.show() once, all subsequent calls to fig.show() don't raise the warning.

Code for reproduction

%matplotlib inline
import matplotlib.pyplot as plt
fig, ax = plt.subplots()
fig.show()

Actual outcome

Plot is shown fine, but the following warning is raised:

/Users/dstansby/miniconda3/lib/python3.7/site-packages/matplotlib/figure.py:445: UserWarning: Matplotlib is currently using module://ipykernel.pylab.backend_inline, which is a non-GUI backend, so cannot show the figure.
  % get_backend())

Expected outcome

The figure is shown fine, so the warning seems unnecessary.

Matplotlib version

• Operating system: MacOS
• Matplotlib version: master branch
• Matplotlib backend (print(matplotlib.get_backend())): module://ipykernel.pylab.backend_inline
• Python version: 3.7.3
• Jupyter version (if applicable): 4.4.0

[jstpierref]

Creating a placeholder for this backend to avoid the NoGUIException or simply continue using fig.show(warn=False). I am new here so let me know if it makes any sense.

[milind-prajapat]

Exact same issue on windows as well

[tacaswell]

I think the correct fix for this is for IPython to implement a no-op manager.show().

[github-actions]

This issue has been marked "inactive" because it has been 365 days since the last comment. If this issue is still present in recent Matplotlib releases, or the feature request is still wanted, please leave a comment and this label will be removed. If there are no updates in another 30 days, this issue will be automatically closed, but you are free to re-open or create a new issue if needed. We value issue reports, and this procedure is meant to help us resurface and prioritize issues that have not been addressed yet, not make them disappear. Thanks for your help!

[oscargus]

I've opened an issue in ipython for this, so closing assuming that the comment from @tacaswell is indeed correct.