My wishlist item for KDE already has a similar feature you can configure: The ability to control transparency via the mouse wheel. This is so close to what I want, it seems doable. I just want to be able to toggle transparency with a hot key. This would be a mouse independent feature. I can toggle transparency of an active window now by using the simple xcompmgr compositor and its companion utility transset-df using the command transset-df -t -p Using a simple bash script, I toggle transparency of an active window on my "Netflix" lappy which uses only a touchpad and no mouse. This is a very handy feature to check on something happening underneath a full screen running. Or even to quickly check the desktop clock will watching a movie full screen.