gtk_print_context_get_hard_margins documentation

[Miroslav Rajcic <support notecasepro com>]

I am trying to use gtk_print_context_get_hard_margins API to ensure that 
my margin settings do not go below printer's hard settings.
The API is documented as:
"Obtains the hardware printer margins of the GtkPrintContext, in units."

My question is: what units are we talking about here?

Most other printing APIs within the GtkPageSetup (like 
gtk_page_setup_set_top_margin for example) accept GtkUnit as parameter 
and return data in desired unit (be it pixels, points, inches or mm).

Regards,
  Miroslav