I totally agree with this, would love to see reg related cleaning entries listed in the results screen so that you can actually see if the entry has cleaned the item or the item wasn't there to start with. At present you just get a "0 bytes removed", which implies nothing was removed, even if reg entry items were.
You can already do that, just tick the "Don't show this warning again" box when it pops up saying Firefox should be closed. Then when you run CCleaner with FF open, it will clean everything else and just skip FF