Apply a background to code with font-lock

Question

I have a command file that uses syntax such as -TAG <ARGS> -TAG- to pass arguments to a sub program. I want to Highlight everything between the opening and closing tags with specific background color to make then easy to find, but not change the faces used for the foreground. Is there a way to do this with Emacs font locks without having to define two faces for everything (one with a background and one without)?

Answer 1

If you specify prepend or append as the OVERRIDE flag in a font-lock keyword, the two faces are joined.