+ optimize redraws (i.e., avoid to redraw if possible)
- (?) change cursor shape according to action
- save to file
- implement auto-arrow 'A' (automatic end-char)
- implement delete 'x' or 'd' 
- manage special chars (DEL/CANC) during text insert
  (also do not print unmanaged chars!)
- load from file
- insert file at position
- get screen geometry
- allow scrolling (both vertical and horizontal)
* implement arrow
* set different line styles (done for hl, vl, corner)
* add status bar
* implement box