From KDE UserBase Wiki

    With KDE you can set any key or a combination of keys to trigger an action on your computer. As an example: when I pause my work I want to lock my screen with the Pause key so my colleagues cannot baggy-pants me. Here is how to do that.

    • Select Shortcuts and GesturesCustom ShortcutsEditNewGlobal ShortcutCommand/URL and enter Pause

    • In the Trigger tab, click on None
    • Press the Pause key
    • Go to the Action tab
    • Enter
      qdbus org.kde.screensaver /ScreenSaver org.freedesktop.ScreenSaver.Lock
    • Click Apply
    • test it by pressing the Pause key

    More Information