Folding doesn't modify the contents of a document. Is that what you're trying to accomplish?
Yes that is what i try to accomplish.
I know that folding is processed like described here.
And I know that an projection can also show additional content not 'only' snippets of the original document.
The projection is build from the original document and changes in the projection is done on the original document.
So i know it is possible to implement something like i want whith the projection view.
But my problem is how to add it is there an extension point or something like that where i can modify/access the projection view of the sse to add additional projection???