Trying to font-lock between parenthesis

[Jules Colding <colding@42tools.com>]

Hi,

I'm trying to do a major mode for MPC(*) files. Before doing anything  
complicated I want MPC files nicely colorised. An MPC file may say  
something like:

    project(optional name) {
      includes += ${PROJECT_ROOT}/src
    }


I want "optional name" coloured differently than the other elements.  
I've tried this:

    ("\\(\(.*\)\\)" 1 font-lock-constant-face t)


But the regexp is wrong as the enclosing parentheses are including in  
the colouring to. What regexp will let me choose the text between the  
parenthesis but not the parentheses themselves?


Thanks a lot in  advance,
   jules


*) http://downloads.ociweb.com/MPC/MakeProjectCreator.pdf