Kogics

The undo thing went away earlier this year when the turtle subsystem was rewritten for better performance (which was required because intricate/complex turtle drawings were starting to take too much time to complete).

The way to deal with mistakes right now is to just rerun your program to (re)make the drawing. If you are making a drawing one line at a time, you are advised to put all those lines into a multi-line program, which you can re-run at will to remake your drawing.

Note - to speed up the rendering of turtle commands (and thus the re-running of your programs), use the setAnimationDelay(n) command (with n = 0, 10, or 100) at the beginning of your program, right after the clear command (which is the recommended first command in a turtle drawing program)

Does that help? More questions?