gtk:print-settings-paper-size (settings)

settings -- a gtk:print-settings object
size -- a gtk:paper-size instance with the paper size

The gtk:print-settings-paper-size function gets the value of "paper-format" setting, converted to a gtk:paper-size instance. The (setf gtk:print-settings-paper-size) function sets the value of the "paper-format", "paper-width", and "paper-height" settings.

 (setq settings (make-instance 'gtk:print-settings))
=> #<gtk:print-settings {1001A0F643}>
 (setf (gtk:print-settings-paper-size settings) (gtk:paper-size-new "iso_a4"))
=> #<GTK-PAPER-SIZE {1001A244C3}>
 (gtk:print-settings-paper-size settings)
=> #<GTK-PAPER-SIZE {1001A24B63}>