VIM folds for Everything except Something

Question

A code is over 2 000 lines full of folds. I select a certain block in Visual mode to which I would like to start writing. However, things around, such as folds, hinter my writing, and I accidentally tend to modify them. Currently, I avoid such mistakes by writing the block in a separate VIM. It is not a real solution, and it gets awkward with too many VIMs open. How can I hide everything except the block in folds?

Answer 1

You can do zMzv or zMzO.

zM closes all folds, zv makes current line visible and zO opens all folds under cursor recursively up to root.

Answer 2

Not exactly what you asked for, but might work...

Map this friend to something:

:vnoremap <Leader>za <Esc>`<kzfgg`>jzfG`<

I have it on leader => z (because it has to do w/ folding) => a (because it stands for "around")

Usage:

Select lines with V, hit leader z a.
Everything above and below will be folded.