This is not a duplicate because this issue is about the stdlib turtle module doing something wrong and needing to be fixed. Also, this issue does not involve threads, at least none that I starting.

"It is not safe to call graphic primitives in event callbacks."

This is a confusing statement. The tutorial at
http://www.tkdocs.com/tutorial/canvas.html
by an experienced tk developer (19 years) includes this:

def addLine(event):
    global lastx, lasty
    canvas.create_line((lastx, lasty, event.x, event.y))
    lastx, lasty = event.x, event.y

Is canvas.create_line a primitive or not?

At the very least, unless I missed something, some change to turtle doc is needed.