This has to be done in the future:

-- There is some memory to be freed. pixmaps, etc. Data should be destroyed
   by the calling program, as it may be used anywhere else.

-- 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

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

-- get rid of some of the annoying printfs