Issue: Source Tab Available When Article Locked

Source Tab Available When Article Locked so the BBCode can be Seen.

I know MediaWiki has this feature for locked articles, and it only hit me when I was copying across the manual to my site, that the lack of a Source option means it is a very difficult matter to copy and paste.

However, I'd not like to see such a feature turned on through the site. Could it be done so it's restricted on a per forum/per namespace basis, or even (though I imagine a lot more work) so that it is possible on a per thread basis (for example through the locked page option)?