When I run the rebuilder to scan for one file in my rom collection, it scans all sets. I would prefer that it would stop scanning upon finding the one file.

How about a change to the rebuilder so that it stops scanning upon finding all the missing roms.

This would allow the rebuilder to finish scanning, when all the missing roms are found.

This could be added by using a "Fast Rebuild" button.

if fast_rebuild && dat->scanned ; then
missing = dat->missing_roms
else
missing = dat->total_roms

:
while (rebuilding) ; do

:
/* If we are not removing rebuilt files
* check if we found all of the missing files
*/
if (fast_rebuild && !Remove_rebuilt_files ) ; then
if (created == missing) ; then
rebuilding = false;
done