Attached patch, issue10199.diff is mostly a copy of Gregor's turtledemo32.zip, with the main difference being that viewer code is in turtledemo/__main__.py so it can be run with just

$ python -m turtledemo

I would like to commit this before any further improvements.  Just as Gregor, I have many ideas on how to improve the demo, but implementing them would be a subject of a new ticket.

Here is a quick list:

1. Add test_turtledemo to unittests.
2. Add means to run all examples in order without user input.
3. Prune the examples: do we need both "tree" and "forest"?
5. Turn the left panel to the expanded list of tests and add a "show source" button to display source in a separate window.
6. Improve names of examples.   "I_dont_like_tiltdemo" is not really a good name. :-)