I am trying to add a "Show Desktop" button on the panel. Super + Alt + RightClick does not work on Gnome Classic. Does anyone know how can I add this button to show the desktop? Also, assigning the keyboard shortcut Super + Ctrl + D in the keyboards / Shortcut did not work. Any help would be highly appreciated. I am a beginner in Xwindow, but proficient in terminal. Since I am using a pretty old machine, unity and compiz have failed to deliver the performance. gnome-classic has been the best so far.