The control panel, in fact, was an application programme disguised as a control panel. In the Application menu, it actually showed up as a separate application; this was the same case when viewed via the About This Macintosh... command (from the Apple menu).
The control panel allowed users to browse and choose a desktop pattern, and to apply it. With the option key held down, the button at the bottom changed to read Set Utility Pattern, allowing it to change utilities desktop pattern as well. (Those that could be changed include the Find File utility.)
The Desktop Patterns control panel was derived from the desktop pattern customisation feature present in earlier versions of the Classic Mac OS, going back as early as System 1. The patterns also were derived in part from the Performa system software; its General Controls control panel allowed users to choose from twelve pre-configured colour patterns.
Under Mac OS X, desktop pictures have seemingly completely replaced desktop patterns. Nevertheless, a Mac OS X Macintosh still allows smaller images to be tiled, thereby mimicking desktop patterns. The switches in Mac OS X: Under Mac OS X 10.0 "Cheetah", switch to the Finder to choose Preferences from the Finder menu, and then adjust settings there. These settings have migrated (properly) to System Preferences as of Mac OS X 10.1 "Puma" (as the Desktop pane and remain in System Preferences to this day (however, beginning with Mac OS X 10.3 "Panther", it has shifted into the newly-merged Desktop & Screen Saver pane).