How to 'code collapse' wiki syntax on Notepad++ (or any other text editor)?

I'm familiar with Notepad++'s code collapse for certain programming languages but recently I've been working with a plain text file that uses with Wiki syntax. For example:

==Heading1==
Content
===Heading2===
Content
===Heading3===
Content
==Heading1.1==

into (when I collapse Heading1):

==Heading1==
==Heading1.1==

I want to be able to collapse these headings and all their contents down at different levels, much like how Notepad++ can collapse tags in HTML, hiding all other tags inside it. I think that's as clear as I explain it any suggestions?

This can be achieved in SynWrite editor. It has complex user-definable lexers (editor is built-in) in which you can create rules such as:

• "from = to next ="

• "from == to next =="

I won't describe how to create lexers for wiki syntax, it's not simple...

In Notepad++ it is possible to create a new User Defined Language. You can do so by selecting

View->User Define Dialog

Choose "Folder & Default" tab. This tab control the style of the default text (text that has no special attributes or meaning) and the keywords that control the folding. A keyword in the Folder Open group will trigger a new Fold group that can be expanded and collapsed. A keyword in the Folder Close group will close any opened group. This explanation (and more..) is available at npp-community documentation