Text editor capable of viewing invisibles?

Question

A recent problem* left me wondering whether there is a text editor out there that lets you see every single character of the file, even if they are invisible? Specifically,

Answer 1

I am not sure as I haven't used it in a while, but I remember that SciTE was a good one that showed me "too much information" for my needs.

Programmer's Notepad on Windows might work.

TextPad (It's nagware, runs on Windows)

I'm not sure which of these will show the hidden characters out of the box, but they're all made for "nerdy" stuff, so I assume that they would work ,at least with a little tweaking. I can verify that Programmer's Notepad does show "hidden" characters.