Links added with one of the functions ps_add_weblink(),
ps_add_pdflink(), etc. will be displayed with a
surounded rectangle when the postscript document is converted to
pdf and viewed in a pdf viewer. This rectangle is not visible in
the postscript document.
This function sets the color of the rectangle's border line.
Parameters
psdoc
Resource identifier of the postscript file
as returned by ps_new().