refer to: http://www.cs.ukc.ac.uk/people/rpg/tsl2/ripple/.  It describes a very 
cool and useful idea called a folding text editor.  "A folding text editor edits 
regular plain text files, and has the ability to fold up lines of text, 
displaying only a single line comment in their place. Folds can contain 
sub-folds, folds can be opened and closed, and folds can be 'entered'.  

Most text documents we write have a hierarchical structure. A folding editor 
gives you hypertext style navigation of that structure. Allowing you to
concentrate on only the parts of your document that are relevant to the editing 
you are doing.

It's very useful for all kinds of documents but when it comes to programming, 
folding comes into its own. In Java for example, you can fold each
method, field declarations, imports etc. The fold browser (left panel in 
screenshot) will then act as a general class browser.

But it gets better. Personally I think Javadoc is a great idea, but I hate 
adding doc comments to my own code because it makes the file twice as big
and gets in the way of reading the code. No problem - I can fold the comments, 
and I don't have to look at them unless I want to."