I like the new "hidden" feature of the BBS, but it doesn't render markup correctly beyond simple text. Here's a "code" inside a "hidden":

print("hi")

Of the several possible uses for hidden, I want to be able to show and collapse long "code" regions, and it doesn't yet work for that. (There are other potential UX solutions for that use case, but that's a valid thing to want to do inside a hidden region, I think.)

"hidden" is not new, and it used to work with "code".
I guess it broke when the indentation got fixed?

in the meantime you can put "hidden" inside "code":

[hidden] print("hello") [/hidden]

(yes, a little ugly)