shift-enter on mpl interactive figure not selecting next cell

A bug from notebook 4.0 has reared its head again. I'm not sure whether it's an issue with matplotlib or notebook, or even whether its the same cause, but it's definitely the same bug:

If you press shift-enter to run cell 1 (containing an interactive figure), then shift-enter does NOT run cell 2.

Previous bug:
https://github.com/jupyter/notebook/issues/949

Minimal example (borrowed from last time): https://gist.github.com/ericdill/537effed420f22af82e0

Other resources:
https://github.com/matplotlib/matplotlib/pull/6752
https://github.com/jupyter/notebook/issues/1124

pip list:

```
Package Version
------------------ -----------
backcall 0.1.0
bleach 3.1.0
Bottleneck 1.2.1
Cartopy 0.17.0
cftime 1.0.3.4
cycler 0.10.0
Cython 0.29.2
decorator 4.3.0
defusedxml 0.5.0
entrypoints 0.3
ephem 3.7.6.0
future 0.17.1
ipdb 0.11
ipykernel 5.1.0
ipython 7.2.0
ipython-genutils 0.2.0
ipywidgets 7.4.2
jedi 0.13.2
Jinja2 2.10
jsonschema 2.6.0
jupyter 1.0.0
jupyter-client 5.2.4
jupyter-console 6.0.0
jupyter-core 4.4.0
jupyterthemes 0.20.0
kiwisolver 1.0.1
lesscpy 0.13.0
MarkupSafe 1.1.0
matplotlib 3.0.3
mistune 0.8.4
nbconvert 5.4.0
nbformat 4.4.0
netCDF4 1.4.2
notebook 5.7.8
numpy 1.15.4
pandas 0.24.1
pandocfilters 1.4.2
parso 0.3.1
patsy 0.5.1
pexpect 4.6.0
pickleshare 0.7.5
Pillow 5.4.1
pip 18.1
ply 3.11
prometheus-client 0.5.0
prompt-toolkit 2.0.7
ptyprocess 0.6.0
Pygments 2.3.1
pyparsing 2.3.0
pyshp 2.0.1
python-dateutil 2.7.5
pytz 2018.9
pyzmq 17.1.2
qtconsole 4.4.3
scipy 1.2.0
seaborn 0.9.0
Send2Trash 1.5.0
setuptools 39.0.1
Shapely 1.6.4.post2
six 1.12.0
statsmodels 0.9.0
terminado 0.8.1
testpath 0.4.2
tornado 5.1.1
traitlets 4.3.2
wcwidth 0.1.7
webencodings 0.5.1
widgetsnbextension 3.4.2
```

Let me know if any additional information is needed.

Start by reproducing the minimal example linked in the issue and compare the behavior with the previous bugs in notebook issues 949 and 1124. Trace whether shift-enter fails in the notebook UI or during interactive figure handling; done means running cell 1 with a figure reliably selects and runs cell 2.

Written by the indexing model from the issue text.