How-to override printer settings

[Michael Cronenworth <mike cchtml com>]

I'm trying to send a print job to tray #2 on a laser printer. It has 
two, real trays.

I've tried two ways of sending the print job to the second tray but each 
time the printer uses the first tray. I understand that each printer may 
have a different source string, but I will always use a Lexmark printer 
and from what I have seen the CUPS ppd has "Tray 1", "Tray 2", etc for 
the source string.

1) Called gtk_print_settings_set_default_source( settings, "Tray 2" ) 
after gtk_print_operation_run().
2) Called set_default_source() before gtk_print_operation_run() by 
creating a new settings struct and calling set_print_settings().

The GTK documentation is not very detailed in this area and Google has 
not been very helpful. Any tips would be appreciated.

Thanks,
Michael