[Programming] Cartesian draw functions

[gabrieljcs]

Still need some help, though... couldn't manage to draw a single line on a plot.
Tried calling from "Program", didn't work -- just drew the line on the screen, on top of everything. Then tried editing inside the app, e.g.:

Code:

EXPORT Geometry()
BEGIN
  IF GETKEY == 30 THEN
     LINE(-1,-1,1,1);
   END;
END;

Didn't work either...
Would you mind clarifying a little bit?