The "Sleep in Background" option is a new feature to OneClick. When this option is turned on in the Preferences box, OneClick will hide all the open palette windows whenever the OneClick application is not active. A small icon will appear on the desktop to remind you that OneClick is sleeping in the background.
To access OneClick when it is sleeping, simply click on the sleeping icon, or select the OneClick application from the Finder's application menu. When OneClick is once again active, the sleeping icon will disappear and all your open palettes will reappear on the desktop.
This option is turned on and off in the Preferences box, and affects all palettes.