This has to be done in the future:

-- Don't draw lines over the edge (might result in serious problems)

-- User defined points, dots, polygons, whatsoever...

-- MORE GCs IF NECESSARY!!!!!!

-- Provide a way to set max and min from outside

-- Data must be destroyed, when widget is destroyed... Hmmm. Might be
   annoying. Let's think it over...

-- engine has to report errors (return value 0 from engine functions)

-- gtk_databox_draw should draw inside the event area only?? May be
   difficult with different dot sizes.

-- fit accuracy and step width must be user's choice

-- get rid of some of the annoying printfs