Tkinter canvas postscript method & fonts

[Richard]

When I use the postscript method of the Tkinter canvas widget, the
dimensions of canvas text on the screen does not match the dimensions on
the printout.  i.e. if a piece of canvas text completely fills the width
of a canvas rectangle on the screen, it only  fills about 70% of the
width of the rectangle on the printout (using Courier 12 point font).

If I could use the fontmap option to the postscript method would I be
able to fix this problem?  If so, how do I create a suitable Tcl array
in Python and then pass it with the fontmap option?

regards,
Richard Townsend