[zyedidia]

Did they just appear as space characters, or did they actually not take up any cells in the editor? Currently some non-displayable characters are rendered as spaces, which is not ideal. I will look into displaying non-displayable characters in a special way (perhaps as `^@`, similar to how Vim does it, or with �, which is meant for this purpose).

[caribousoup]

I think they were appended to the end of each line, so unfortunately that would make it non-obvious that something was there. If they were rendered as spaces that would explain not being able to see it. Displaying them as � would be an improvement.

Again, this was awhile ago, but I don't think they were single characters, it was a sequence of characters.

[superchink]

Is it possible that it was a matter of changing the line endings? Some applications can be quite sensitive to different line endings… sounds suspiciously like that?

https://en.m.wikipedia.org/wiki/Newline