Sometimes it's a bit difficult to find the caret with Source Editor, would be much nicer if it slightly highlighted the current line.
Like in the second example of this page:
This is going to be fixed by the latest upstream Orion code, see bug 692807.
This is now fixed. Bug 692807 landed.
Current line now has a light blue highlight. VERIFIED on Build identifier: Mozilla/5.0 (X11; Linux i686; rv:10.0a1) Gecko/20111107 Firefox/10.0a1