There is a great Windows utility called Hide Window Hotkey - It lets you make an application disappear from the desktop, and requires a password to make it re-appear.

Unfortunately, I don't see anything like that for Ubuntu.

I installed Compiz & I'm playing around with the settings & reading the manual, but I can't seem to make it do what I want.

All I need is to hide a running application on an "always-on" machine, and be able to summon it back when I want, but only through a hotkey combination & a password - NOTHING visible. In other words, if anyone else uses the computer, they should have NO idea that the app is running in the background. Only I should have the ability to make it appear.

Is there a program that lets you do that, or a script, or a Compiz configuration?Any advice would be much appreciated.