When CLIM renders the graphics and text in the drawing plane onto a real display device, physical limitations of the display device force the visual appearance to be an approximation of the drawing plane. Colors that the hardware doesn't support might be approximated by using a different color or by using a stipple pattern. Even primary colors such as red and green can't be guaranteed to have distinct visual appearance on all devices, so if device independence is desired, it is best to use make-contrasting-inks (which produces designs of different appearances) rather than a fixed palette of colors.
The line style and text style respectively control the region of the display device that is colored when a path or text is rendered.
Common Lisp Interface Manager 2.0 User's Guide - 20 Sep 2011