facemenu-add-face-function

facemenu-add-face-function is a variable defined in `facemenu.el'.
Its value is

nil

• This variable may be risky if used as a file-local variable.

Documentation:
Function called at beginning of text to change or nil.
This function is passed the FACE to set and END of text to change, and must
return a string which is inserted. It may set `facemenu-end-add-face'.

You can customize this variable.