c_gtk_page_setup_unix_dialog_set_page_setup

Undocumented in source but is binding to C. You might be able to learn more by searching the web for its name.
__gshared extern (C)
void function(GtkPageSetupUnixDialog* dialog, GtkPageSetup* pageSetup) c_gtk_page_setup_unix_dialog_set_page_setup;

Meta