Device discovery of the "bluetooth" CUPS backend does not work

Binary package hint: bluez-cups

I am on Karmic, and I can set up a Bluetooth printer only manually by running the "bluetooth" CUPS backend from the command line with

/usr/lib/cups/backend/bluetooth

and then pasting the URI into the field for individual URI input in system-config-printer ("Others" in the device list). Then I also need to choose manufacturer and model manually. My expectation is that I only need to click the printer's make model name in the devices list and choose "Bluetooth" under the connection types and then the driver gets selected automatically as it is the case for the same printer on USB or WLAN.

I have found out why it does not work.

First, the CUPS Bluetooth backend asks the bluez D-Bus service whether there are printers available and which device ID they have. The access permissions for the bluez D-Bus service do not permit the CUPS system user "lp" to access, and exactly as this user the Bluetooth backend is running. Therefore I have modified /etc/dbus-1/system.d/bluetooth.conf to grant this permission.

Second, the output of the CUPS Bluetooth backend was not very good for the printer setup tools doing the right thing. I have patched the backend to let the device class of the Bluetooth printers to be "direct" and not "network", as users expect a Bluetooth printer rather under the local printers than under the network printers. I have also filled the make-and-model field instead of putting a hard-coded "Unknown" there.

The debdiff for these fixes on the bluez package is attached. Please apply it to the package to make Bluetooth printing just work. Thank you.