Looking for a lightweight text editor with collapsable headers

I'm looking for a light-weight text editor where I can collapse a paragraph of data into the header. So I see a list of headers,  can click on one and the paragraph folds up-into or down-from the header.

Programing  (IDEs) development environments do this.

I'm looking for a "note pad" type utility with this feature that includes spell check.
And I want to run it from a thumb-drive so "standalone" is good.

Collapsible Outline might be a better way to say it.

Any ideas?

Scott