I have installed a few other desktop environments on my Ubuntu 16.04 machine, and after doing so, I discovered that Super doesn't work anymore! It doesn't pull up the menu on any DE. I also found out that Alt+Tab doesn't work anymore either. How would I go about fixing this? In settings, these shortcuts are not displayed, so I have no clue how to. Thanks!
Edit: I have installed the following DE's:
The keyboard shortcuts were working after I installed GNOME 3, GNOME Classic, Unity8-Mir, and Budgie Desktop. Super and other system shortcut keys worked with all of them (might it have something to do with Compiz?). After installing the other DE's, it was then that I noticed the keys weren't working. It's only some combinations that do work, I primarily use GNOME 3, and I found out that Super+S opened the activities view. But in Unity, I found out that Super+W wasn't working. I am very confused, I think that some system shortcuts work, and some do not. I also noticed that the Esc key isn't working. Even playing a flash game in Firefox, Esc is just not read!
I would like to get these keyboard shortcuts back for any DE that uses gnome shell. So Unity, Gnome 3, Gnome Classic, Budgie Desktop, and Cairo-Dock. I don't care about Unity8-Mir, though.