I agree with you.

I've got my Emacs set up to display in "bold, fluo foregound and a dark background underlined by a pink line" (yes, literally that obnoxious) any character which is not part of a list of characters I consider to be acceptable. And it's configured to show any "zero width" character as if it had a width. So any "invisible character" as well as any "invisible zero width character" does appear as a black square, underlined with a pink line.

And that for any buffer/file.

Can you share that config? Sounds useful!

Sure... For a start I have my scratch buffer showing a few Unicode characters, one trailing spacing character on purpose (to be sure I can see it's highlighted), a zero-width-non-joiner 0x200C and an Hangul filler 0x3164 (may add some from TFA btw). This helps me quickly verify, upon startup, that my setup is working.

I configured all that literally years ago so I don't remember where's what but here's what I've got:

    ;; probably cargo-culted from somewhere
    (update-glyphless-char-display 'glyphless-char-display-control '((format-control . empty-box) (no-font . empty-box)))
    
    ;; See https://emacs.stackexchange.com/questions/65108
    (set-face-background 'glyphless-char "purple")

And then I've got this too (requires markchars.el):

    (markchars-global-mode)

With:

    (defface markchars-heavy
      '((t :underline "magenta"))
      "Heavy face for `markchars-mode' char marking."
      :group 'markchars)

It should get you started.

(and, yup, I know it's overkill but I like it that way)

I use a DOS text editor for this, where no Unicode support is an advantage. The majority of the time I'm dealing with plain ASCII anyway.

Vim does not display them all. The only program I checked which displays all such characters is `less -U`. You can test using this file:

https://gitlab.com/nervuri/nervuri.net/-/raw/master/gopher/z...

Thanks for this! Good to add to the ol' repertoire (:

Looks like the only one Vim misses is U+17B5? Though it there could be more not listed there. Unicode is a deep dark forest.

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For others readers, here's a non-gopher version of the article linked inside: https://nervuri.net/stega

Also 061C, E0001, E0020...E007F. And probably others, yes. The list at https://invisible-characters.com/ might contain more.

> Unicode is a deep dark forest.

Oh, indeed.