I just installed the GNOME tweak tool on Ubuntu 16.04 and only changed that the top bar should show calendar and that the Alt key should not function as the windows key. Now my mouse won't click on buttons inside applications. I get the right icon when hovering across buttons, but nothing happens. Interestingly enough, I can drag windows and click buttons in the menu bar.
I've tried uninstallign GNOME tweak tool and restarting, but without any luck. Any advice? Thanks!