Bug [5.5.1f1 under Ubuntu 16.04] MonoDelevelop doesn't launch

I installed Unity 5.5.1f1 three times in a row, thinking that something had gone wrong but it appears that, whatever I do, MonoDevelop doesn't start from within editor. It doesn't start at all anyway.

I labelled it "bug" but it's something different; a bug does not happen systematically.

Somebody posted a way to fix the situation but I don't understand what to do with it. It's here (I hope the author won't mind that I post a link to it here) : https://forum.unity3d.com/threads/guide-how-to-use-monodevelop-as-default-ide-under-ubuntu.440449/

 

In the Preferences->External Editor section, use the browse button and locate the monodevelop binary shipped with Unity. it seems the 'use internal monodevelop' setting does not find it correctly.

 

Sorry, forgot about that; it's the first thing I did and it doesn't work either.

 

Do you have the dependencies for MD? (They're not shipped with unity today - we only have them listed as "Recommends" in the debian package.)

apt install monodevelop mono-reference-assemblies-2.0 mono-reference-assemblies-3.5 may get you somewhere.

 

Ah, that could be it, since Unity was installed through the Ubuntu "store" (sorry, I don't remember it's exact name. The deb package is open with the software installer and nothing is listed there.

Thanks!

Anyway, I consider switching to Linux Mint, I hate Unity, the user interface that is installed by default with Ubuntu and I don't want to bother with installing a different one. Linux Mint Cinnamon suits me better.