The key to Control is knowing that anything you want to do will work. I disagree with the "licking a rainbow" part. Unless you expect it to de-synchronize it will not. The only thing that will happen is that your subconscious mind, along with its schema's will create the outcome, whether it makes the rainbow taste like ice cream, brownies, or anything else all depends on your subconscious. Of course you can control the outcome with expectations as well. Dreams are not extremely fragile AT ALL. Maybe for you because of your expectations and past experiences, but do not place that mental block on other Lucid Dreamers, because it is not true. Dream Control is all based off of how much you believe. If you simply "know" anything will work without a doubt, it will. That is the logic; that it is your dream therefore you can control all of it. There doesn't have to be any solid reason. What you are doing is creating a huge obstacle if you do feel there needs to be good logical reasoning. It isn't called the "Dream" world for nothing. It is a place where you can do anything, and where you are limitless. You set the limits, you make the rules.