Lesson 25

 Lesson 25 is a lovely and simple code that moves an alien saucer

around earth. but it did open a troublesome issue for me. What could

a Tcl error be. TCL stands for Tool Command Language; and it is the

language used to code Tkinter!!

                                                                

The lesson code:

                                                            

                                                                         

                                                                                      

In the code -as presented - the alien vessel bounces off the sides, in an endless loop.

But one can change the size of the canvas. I have a 500x500 image coded to a 500x500

canvas window; all well and good. Bt if I make the canvas size narrower by 50, the vessel

- a 60x44 image - largely disappears to the right. Things to watch if one is making a game.