It doesn't look like much but quite a few hours of work went in to that. If you knew what you were doing I think you could create that in less than 15 minutes and hopefully one day even I'll be able to do that.
This is actually a control I'm going to use in a config editor utility I'm making for work. It allows you to collapse or expand blocks of configuration so that you can read through the file more quickly and get to the bit you want to edit. Hopefully I'll also find a use for it related to games :)