void gtk_print_operation_set_export_filename ( GtkPrintOperation* op, const char* filename )
Sets up the
GtkPrintOperation to generate a file instead
of showing the print dialog.
The intended use of this function is for implementing “Export to PDF” actions. Currently, PDF is the only supported format.
“Print to PDF” support is independent of this and is done by letting the user pick the “Print to PDF” item from the list of printers in the print dialog.