facemenu-complete-face-list

facemenu-complete-face-list is a compiled Lisp function in `facemenu.el'.

(facemenu-complete-face-list &optional OLDLIST)

Return list of all faces that look different.
Starts with given ALIST of faces, and adds elements only if they display
differently from any face already on the list.
The faces on ALIST will end up at the end of the returned list, in reverse
order.