Not sure if this is the right place to put this, but I 'kinda' programmed the Agent Time Detail page to display billable time. You can check it out on this link:
http://www.vicidial.org/VICIDIALmantis/view.php?id=550
I am not a programmer, but I kinda' know my way around mysql, so the actual calculations were done in the database and not as part of the php script which seems to be the rule (which I totally support).
It has a flaw...., if you change the billable-non-billable status in the pause code screen and run a report on dates prior to the change date, the values will be different as if running the report prior to the change. The script will look for the current non-billable codes.
Perhaps some programmer could do the 'right' coding....