search for a better php source code viewer

Hi, I'think anybody knows highlight_file, highlight_string or show_source, but these are not good enough. For an application I need a more advanced technique, which includes line numbers and let me control all formatting instructions (not only <font color...>). Is there any script out, written in PHP (and supports PHP and HTML), that can be expanded by highlighting my own functions/classes, my own XML-Tags etc.? Thanx for any idea, Joerg