This is mostly for KDE users. It is improved alternative to WIN key or Alt+TAB key for Linux with KDE. Instead of using bind for fullscreen 1|0 you can make this one. It is very helpfull and works perfectly.
Go into System Settings > Shortcuts and Gestures.
Find the option on the left, labeled "Global Keyboard Shortcuts".
Then on the right side, where is "KDE Component" , select "Kwin" from the drop down box.
Search for: "Show desktop"
Use your preferable keyboard shortcut. (Meta + D or so )
*meta = winkey.