HKCU\Control Panel\Custom Colors
Represents a custom color.
To change the custom colors, double-click Display in Control Panel, and then click the Appearance tab in the Display Properties dialog box. Click the Colors list, and then click Other.
The Color entry is a variable representing the entries under the HKCU\Control Panel\Custom Colors subkey. It does not actually appear in the registry. This variable entry displays information that is common to the entries in the Custom Colors subkey.