I apologize for making it too complicated for you. You seem to be having trouble catching my meaning, so I feel we are just repeating ourselves. Let me try to approach this in a different way.

For God to create such a thing as human kind, He would have to create a physical world, governed by physical laws, yes? So the physical laws of the universe are of His creation. According to those physical laws, humans cannot become invisible. If He wanted to create a world in which His creations could do anything they could possibly conceive of, He would essentially be filling the universe with little Gods. Without any limitation on their abilities, they would be indistinguishable from Himself. What would be the point of creating them, then? Instead, God created a physical world governed by physical laws, and physical beings within it who are subject to those laws; He created something outside of Himself, thereby creating the possibility that His creations could come to know and love their creator. Invisibility is not a power granted to us within the confines of the physical universe, but that has nothing to do with the issue of free will.

Imagine an RPG (not sure if you play video games, but you strike me as the sort that would), the Elder Scrolls series for example, as that's my favorite. The world is set up with physical laws that govern it, like gravity and the passage of time, and define an order to what is possible and what is not. Without these underlying rules, the game would make no sense, it would be unintelligible and therefor unplayable. Given the world as it is set up, you're free to play as you wish. You can be an evil character, killing innocent villagers for no reason, raiding merchant shops, cheating your guild masters, etc., or you can choose to help other characters on their missions, respect the rights of innocents, and so forth. The fact that you can't turn your character into an artichoke if you wish has no bearing on your free will in the moral sense. Likewise, your inability to become invisible in our actual world is simply a consequence of the way that the universe is set up. Without governing physical laws, there would be no intelligible space for "game play". This has nothing to do with your free will to act morally or immorally in the world in which you are placed.

Of course, in the Elder Scrolls world there are ways to become invisible: potions, scrolls, etc. In the parameters set up in that world, it's a possibility. In our world, we have a different set of parameters. I'm not aware of any technology currently in existence that would grant us invisibility. I'm pretty sure that's not your point, though. I think you're trying to say that physical limitations in this world are themselves restrictions on free will. This confusion of yours was probably my mistake in not specifically indicating that by free will, in this case, I meant moral free will. To compare the freedom to choose to be invisible and the freedom to choose to kill are two separate things. One is a physical ability, the other is a moral choice. If you're trying to make the point that physical limitations are limitations on free will, then I would reiterate that those physical limitations are consequences of the existence of a physical universe in which such a thing as man kind is possible, and in which moral choices can exist. You're comparing apples and oranges.

You keep bringing up Hitler, and I've been trying to tackle that subject in a broader sense, but I'll go ahead and address him specifically. Hitler entered into power through widely recognized, legal, democratic means, and he used his position not to directly kill millions of people, but to order many others to do so on his behalf. This means that it wasn't really Hitler who directly killed millions of people, but rather many people exercising their own free will to commit murder or support such acts. But if I'm reading you correctly, you're just using Hitler as a placeholder for those who commit evil acts, so my original argument remains, which you claim I have not laid out. But I've already laid out my argument for why God grants us free will. To put it as simply as I possibly can, God gives us free will so that we have the ability to choose the good. This freedom necessitates the ability to choose evil. If you don't remember, go back and reread. I'm repeating myself here again and again on this point, and you seem to be pretending I never said anything about it. If you don't think it's a good argument, please explain why. If the point of human life on this earth is, as the Christian believes, to freely choose God (and therefor the good), then the possibility to not choose Him must exist. Hitler, his followers, and others throughout history are examples of people choosing evil.