gtk:printer-hard-margins (printer)

printer -- a gtk:printer object
top -- a double float for the top margin
bottom -- a double float for the bottom margin
left -- a double float for the left margin in
right -- a double float for the right margin

Retrieve the hard margins of the printer, that is the margins that define the area at the borders of the paper that the printer cannot print to. This will not succeed unless the details of the printer are available, see the gtk:printer-has-details and gtk:printer-request-details functions.