Thread:Project:Support desk/Suppressing replacement of line breaks with spaces/reply (2)

Browser is Chrome 17, Internet Explorer 9 and Firefox 10; program is Word 2010, Notepad (Windows 7) and Notepad++ 5.9.2. But copying and pasting from within the edit box doesn't replace line breaks. I'm guessing that the wiki is silently inserting a placeholder character at the end of each line in its own edit box; if that's not present (i.e. it came from a regular plain or rich text editor), it filters the break out.

I think it's a wiki configuration thing, since this behaviour isn't present on any of the WMF wikis (that I know of). What do I change in the configuration options to make it go away (either per-user or globally)?