[Python-modules-team] Bug#847225: jupyter-notebook: Strange square appears when displaying matplotlib inline plots

[Paride Legovini]

Package: jupyter-notebook
Version: 4.2.3-1
Severity: normal

Dear Maintainer,

Thanks for this long awaited package.
I noticed that when I plot an inline interactive plot with matplotlib
(using the "%matplotlib notebook" magic command) a black square appears
on all the cells, as in this screenshot:

http://prntscr.com/dg36oy

The black square stays there even if I open a menu (like the Edit menu),
staying "over" the menu.

I'm using Chromium, it seems that Firefox is less affected by this
little but annoying problem. I can always reproduce the issue with
this minimal code:

```
%matplotlib notebook

import matplotlib.pyplot as plt
import numpy as np

t = np.arange(0.0, 2.0, 0.01)
s = np.sin(2*np.pi*t)
plt.plot(t, s)
```

When I start jupyter-notebook I get the following warning:

/usr/lib/python3/dist-packages/ipywidgets/__init__.py:67:
RuntimeWarning: To use the widgets with your installed Jupyter Notebook
version, please install ipywidgets 4.x or earlier.
version, please install ipywidgets 4.x or earlier.""", RuntimeWarning)

but I don't think it's related.
If you need further details or feedback just let me know.

Thank you,

Paride

-- System Information:
Debian Release: stretch/sid
  APT prefers unstable
  APT policy: (500, 'unstable'), (1, 'experimental')
Architecture: amd64 (x86_64)

Kernel: Linux 4.8.0-2-amd64 (SMP w/4 CPU cores)
Locale: LANG=en_US.UTF-8, LC_CTYPE=en_US.UTF-8 (charmap=UTF-8)
Shell: /bin/sh linked to /bin/dash
Init: systemd (via /run/systemd/system)

Versions of packages jupyter-notebook depends on:
ii  python3-notebook  4.2.3-1
pn  python3:any       <none>

jupyter-notebook recommends no packages.

jupyter-notebook suggests no packages.

-- no debconf information