Hi Andrej,
> > I have tested the attached program, however, the problem still persists. > The > pieces still have invisible walls. I must also mention that the pieces also > behave like this when you approach the walls of the playing area. > > I am sorry, I did not understand whats is the problem. Yes, the pieces collide with each other and with the margins of the playing area (except in the infantile level). When they collide, the moving piece rotate automatically. And the pieces are coming together when are close together. Everything is clearer when the Level 2 is used (novice level). Regards! I. De Marchi