Hello everyone, I’m building a small fractal visualisation app in ocaml, but I encounter many problems with the graphics package. First, plot (size_x / 2) (size_y / 2) doesn’t actually plot in the middle of the screen… Any idea why? Then, using the following code if key_pressed () then begin match read_key () with | 'q' -> raise Exit | 'o' -> scale := !scale *. 2. | 'i' -> scale := !scale /. 2. | 'l' -> mid_x := !mid_x + 100 | 'r' -> mid_x := !mid_x - 100 | 'u' -> mid_y := !mid_y + 100 | 'd' -> mid_y := !mid_y - 100 | _ -> () end done; in a while true loop behaves randomly, ignoring some key presses, and repeating some… Is there something that I did wrong? Thanks a lot, Andrea.