After creation, a printer shell widget must be realized by invoking realizeWidget. The shell responds with a map callback to indicate readiness for job control messages. At this point the shell can be used to start print jobs.

Because printing is implemented as a set of user-interface operations on a printer display, the application must run the user-interface event loop to allow callbacks to be sent to the printer shell. The application can either fall back to the event loop after realizing the shell, or it can run a new event loop in place until printing is complete. Printing operations cannot be performed by processes other than the user-interface process. For more information see The user interface process model.

After reception of a map callback the application sends startJob to the shell, which begins a new document with the title specified by the shell's title resource. The title is used to identify the document within the operating system, and typically includes the name of the application producing the document. Title changes only take effect prior to the beginning of a new print job.