Under Community Review

Mandatory plaintext fields should not be marked 'filled in' when a user pastes a tab character (or similar)

Some users try to avoid filling in mandatory (single line, plaintext) fields by pasting a tab character from the clipboard. Bad user behaviour, in my opinion, but they do. Unlike spaces, tabs are not trimmed before validating. What characters are invalid then? I think a white-list (containing all visible characters) could be an option. I can fix this in custom code, but I think this should be in the core system.