Code Browser is a folding and outlining editor.

The editor is between a traditional text editor, a smalltalk class browser and
a web browser like mozilla. It displays a structured text file (marker-based
folding) hierarchically using multiple panes.

It is especially designed to keep a good overview of the code of large
projects.

It supports syntax highlighting for C, C++, C#, VB.Net, Java, Python, Ruby,
Pascal, TeX, Makefile, XML, HTML and CSS. Custom syntax highlighting can also
be added.

WWW: http://code-browser.sourceforge.net/