I think about a patch to issue the foldingPreview in case of unfold when done by click on the icon bar. Unfortunately would that need some bigger changes at the toggleFolding functions to return what was done.

Oops! Noticed that we have now some odd behavior when issued the toggle child action, will take a look.

I must confess, I am a bit confused what this patch should improve.
Could you tell again which concrete issue it fixes?
And why is the delete not useful?

Ok, I see, I tried it a bit more and yes, now the folding start/end tokens are highlighted on unfold.
Btw., is it intentional that the folding start/end tokens are only sometimes highlighted on folding, still?

e.g. not for the

if (trueValues.contains(val)) {
    *result = true;
    return true;
}

case?

And why is the delete not useful?

After one month, no idea on first sight, sorry. Guess it is deleted prior or later anyway/already.

is it intentional that the folding start/end tokens are only sometimes highlighted on folding, still?

I don't think so, no. But can't reproduce the given example. Looks working here.

OTH Seems my stated "With this patch behaves the unfold like the fold to highlight the start and end marker" only valid when fold by Short-Cut and not by mouse click on the left border.

So, compare where the cursor is when click on the left border. Without patch on pos 0 (first column), with patch just before the open brace.

I was often slightly irritated when unfold something. "What exact was now unfold?" The text jumps to quickly. A soft, fluid animation may nice, but not so easy to do. So I came up with this idea.