fv can't quit properly (crash of gnome-shell)

[Autiwa]

I'm using Ubuntu 18.04.4 LTS.

I installed fv using the package ftools-fv (version: 5.4+dfsg-4)

Whenever I open the software to visualize a .FITS file, it works.

When I close the app (close the last of the 3 windows fv open), the system freeze. I just tried again and it simply froze and went back to normal.

However, when I did the experiment again from the command line, I got the following message, with no clear error at the end. I don't know if it's usefull. In case:
```bash
$ fv
XPA$WARNING: xpans needs to be running on this machine.
Please start xpans using the command:
 xpans -e -p 14285 -l /tmp/.xpa/xpans_14285.log
Once xpans is running, register all xpas in this process using:
 xpaset -p 7f000101:42893 -nsconnect
For now, contact pow using: xpaset 7f000101:42893 .. or xpaget 7f000101:42893 ..
For now, contact fv using: xpaset 7f000101:41703 .. or xpaget 7f000101:41703 ..
```

NOTE: I did not try to open a specific .FITS file, it crash even with no file opened.

Finally, this happen to me for months if not years. This happened to me using 2 different computers.

[Launchpad Janitor (janitor)]

Status changed to 'Confirmed' because the bug affects multiple users.

[AlwaysTired (alwaystired)]

I've also experienced this bug for at least a couple of years now, on two different computers.
Sometimes I manage to quit fv without crashing. In most cases everything freezes for a moment (looks like a gnome restart). Sometimes it logs me out of the Ubuntu session. Killing the "wish" process from the system monitor closes the program without further problems.