print margin (right/leading) side not correct

In gschem I printed a default A-sized drawing via lpr to HP 7410 OfficeJet printer.
I chose Type = "Extents with margins" in print dialog.
The result was image clipped off the right side of title block.

If I place a Text character right of title block about one major grid spacing, the
right side of title block is printed.
I know that HP DeskJet printer family have minimum required spacing on leading and trailing
edges of (I think) 0.5 and 0.66 inches respectively. The output I got showed the horizontal
line of the title block stopped at about 7/16" from edge of paper. So, gschem is ignoring the right
margin altogether, or the margin used is too small. I tried to find it in 'rc files but
could not find any place where the values of the margins were defined or listed.