Line break override doesn't work

Send Tab URLs 2.3

The line break override (by setting a pref in about:config, `extensions.aecreations.sendtabs.message.line_break`) doesn't work.  If, on Linux, this is set to "\n", the backslash character and the lower-case letter n are displayed literally, when the URL list is copied to the clipboard and then pasted into a text editor (e.g. KWrite on a KDE-based desktop environment).
