feature request: hierarchical visual markings

[albertz]

E.g. imagine you want to print some Lisp code on the console.
You can cover everything inside brackets (...) in a logical block, e.g. print \033]110\007 before every ( and \033]111\007 after every ) (or maybe some other reserved escape code just for that purpose).
I would like to have some graphical support for that, like you have in some editors. I.e. when you hover with the mouse over some part, it will highlight the whole logical block, maybe excluding sub blocks, so that you visually see the matching start and end brackets.
This is what I would like to have for now, but see e.g. here for some other ideas (but I think I would prefer any of these hightlightings only when you hover the corresponding text).

Another extension which I could imagine for this is some automatic folding logic in some way (related to #54), where it either prints ... and when you click on it, it will print the contents, and another click again folds it to ... (maybe you can already get this via #54 but I can imagine that just some logical block which has this built-in would make it simpler). However, just the hover highlighting would be enough for me for now.

[PerBothner]

A fairly simple idea: when you hover over a button, it adds another classname to all the elements that would be hidden (where the button to the clicked). You can then easily style those elements.

Another (simpler/better?) option: when you hover over a button, it adds a classname to the immediatly enclosing logical block (pprint-group), which could also be styled.