Reference: pmAddSizeToEdges
pmAddSizeToEdges(pm, r, b, l, t) returns the pixmap pm with r, b, l, and t black pixels added to the right, bottom, left, and top, respectively.
pmAddSizeToEdges(pm, r, b, l, t) returns the pixmap pm with r, b, l, and t black pixels added to the right, bottom, left, and top, respectively.