gtk_printer_get_hard_margins_for_paper_size() is not external
Bug https://bugzilla.gnome.org/show_bug.cgi?id=686109 added _gtk_printer_get_hard_margins_for_paper_size() in gtkprinter-private.h in gtk+-3 and gtk_printer_get_hard_margins_for_paper_size() in gtkprinter.h in gtk+-4.
But gtk_printer_get_hard_margins_for_paper_size() in gtkprinter.h is not preceded by GDK_AVAILABLE_IN_ALL or any other GDK_AVAILABLE_IN_ macro. Therefore it's not available for calls from code outside the gtk+ load module. Isn't it meant to be public API in gtk+-4?