Is it normal that the tanks could get stuck inside the other tanks? And If those orange blocks are in the way, the tank that got stuck can go through them.

Very good scenario, but there a some things that could be fixable. Why are the "color balls" ovals and why is the mouse ball acting weird? If you are interested, I could upload a paint scenario without mouse problems and round color balls, so you could take a look at it (+ the source code).