mh-font-lock-add-keywords
    
    mh-font-lock-add-keywords is an alias for `
font-lock-add-keywords' in `
mh-compat.el'.
(mh-font-lock-add-keywords 
MODE KEYWORDS &optional 
HOW)
Add highlighting 
KEYWORDS for 
MODE.
MODE should be a symbol, the major mode command name, such as `c-mode'
or nil.  If nil, highlighting keywords are added for the current buffer.
KEYWORDS should be a list; see the variable `font-lock-keywords'.
By default they are added at the beginning of the current highlighting list.
If optional argument 
HOW is `set', they are used to replace the current
highlighting list.  If 
HOW is any other non-nil value, they are added at the
end of the current highlighting list.
For example:
 (font-lock-add-keywords 'c-mode
  '(("\\<\\(FIXME\\):" 1 'font-lock-warning-face prepend)
    ("\\<\\(and\\|or\\|not\\)\\>" . 'font-lock-keyword-face)))
adds two fontification patterns for C mode, to fontify `FIXME:' words, even in
comments, and to fontify `and', `or' and `not' words as keywords.
The above procedure will only add the keywords for C mode, not
for modes derived from C mode.  To add them for derived modes too,
pass nil for 
MODE and add the call to c-mode-hook.
For example:
 (add-hook 'c-mode-hook
  (lambda ()
   (font-lock-add-keywords nil
    '(("\\<\\(FIXME\\):" 1 'font-lock-warning-face prepend)
      ("\\<\\(and\\|or\\|not\\)\\>" .
       'font-lock-keyword-face)))))
The above procedure may fail to add keywords to derived modes if
some involved major mode does not follow the standard conventions.
File a bug report if this happens, so the major mode can be corrected.
Note that some modes have specialized support for additional patterns, e.g.,
see the variables `c-font-lock-extra-types', `c++-font-lock-extra-types',
`objc-font-lock-extra-types' and `java-font-lock-extra-types'.