User-Agent: Mozilla/5.0 (Macintosh; U; Intel Mac OS X 10.5; en-US; rv:1.9.0.1) Gecko/2008070206 Firefox/3.0.1 Build Identifier: View Source should show line numbers in a gutter to the left. It should be possible to toggle the display of the numbers on and off. Reproducible: Always

This is a DUPE of bug 246620, unless you've got different plans here.

Verified Dupe

Hey guys, I don't know if it matters, but I was attempting to create bugs for these feature requests (view source enhancements) that were specific to Firefox. This is partly in response to bug 15364 (show line numbers in view source for SeaMonkey). That bug is resolved fixed for Sea Monkey, but it's clearly not fixed for Firefox. This is not to say that it's useful to have Firefox-specific bugs for these feature requests. You guys are the experts, so I'll defer to your judgement here. I just wanted to explain my thinking for the record.

Bug 246620 isn't a SeaMonkey bug (per the last few comments there and its summary), isn't resolved, and is pretty much exactly describing the same thing that this bug is, so I don't think there was a need for a new bug in this case.