Test result

Has an option "For your eyes only" for each Slip (which then shows an eye icon near the total in line items), and one can show such unbilled items on some reports, however one can't AFAIK show unbilled items easily together with billed ones on an invoice. I mostly don't want "For your eyes only", I want plain ol' unbilled, so that I can show myself and clients what they are NOT paying for (example, lots of time spent debugging Drupal modules that can't be billed). I want to be able to easily show unbilled and billed side-by-side, at least in reports (not necessarily in invoices, but I'd like that, too sometimes).