The following issues are on my list of things to do in one of the
next versions:

- Background images (default, fit, tile, center).

- Make proper installation procedure for CGI script.

- Text font handling.

- Improved security (when the script is used as CGI script).

- Check out the GNU plottools.  Maybe use libplot instead of (or together
  with) the gd library.

- Arbitrary origin, with rectangular or polar coordinates.