Ok ... I have had some time to think about this ...
I can do just such a program, BUT even though I would love to do it ... I cannot justify the time involved in doing so.
To properly develop, code, debug and test a program would take several hours .. I'd hate to even try to estimate it without some in depth study of the situation.
However, here is what I suspect it would be ...
Program Flow
Program Starts at boot and monitors top level windows
When AutoCAD is top level window
Grab document name
Start timer
Open DB
Check for name in database
If name exists increment time entry
If name does not exist, add entry increment time entry
When drawing loses focus, stop timer, stop DB incrementation, close DB
When drawing changes, reset timer, change DB entry and repeat ...
There it is .. all spelled out in concept ... all it needs to be is implemented ...
If I find time I may do something .. or defer it to RCI for a paid program as a time sheet management program.