+ optimize redraws (i.e., avoid to redraw if possible)
- (?) change cursor shape according to action
- auto-arrow 'A' (automatic end-char)
- load from file
- read file at point
- visual selection
  - crop
  - fill
  - delete
  - yank/put
- undo (by storing lines changed across insert/remove operations)
- manage special chars (DEL/CANC) during text insert
  (also do not print unmanaged chars!)
- get screen geometry
- allow scrolling (both vertical and horizontal)
* write to new file / default file
* delete -- 'x' 
* save to file
* implement arrow
* set different line styles (done for hl, vl, corner)
* add status bar
* implement box