[cups] OS X dialog to add a printer

[Jacob Marble]

CUPS Cloud Print <http://www.niftiestsoftware.com/cups-cloud-print/> (CCP)
is a backend to Google Cloud Print printers. It could work better in OS X,
so that's what I'm doing today.

When the user tries to add a printer using the standard OS X (10.9) dialog
("default" tab), CCP properly provides a list of printers to cups-deviced,
as proven in the OS X dialog.

However, when the user selects a printer, invoking [cups-driverd list ...],
CCP returns something wrong such that the "Name" and "Location" fields are
properly pre-filled, but the "Use" field (backend/driver/PPD) falls back on
"Generic PostScript Printer" with the message "The selected printer
software isn't from the manufacturer blah blah blah."

The PPD is generated dynamically with [cups-driverd cat
cupscloudprint:blah]. Calling this by hand works.

1) Is this the right place to work on OS X GUI-specific issues?
2) What does the OS X dialog look for that could be missing? More IEEE-1284
info?
3) Is this documented publicly somewhere? I tried the CUPS documentation
and Apple's OS X documentation.

Thank you,

Jacob Marble
Google Los Angeles