custom-known-themescustom-known-themes is a variable defined in `
custom.el'. Its value is
(user changed)Documentation: Themes that have been defined with `deftheme'. The default value is the list (user changed). The theme `changed' contains the settings before custom themes are applied. The theme `user' contains all the settings the user customized and saved. Additional themes declared with the `deftheme' macro will be added to the front of this list.