A good friend, Gabe Wilson, showed me a very cool trick native to OS X regarding saved files. If you look at the top left corner in the close, minimize, maximize bubbles you may sometimes see a small dot in the middle of the red circle. This dot is telling you something. It means the current document is not saved. So if you press the red button and that dot is in it, very bad things will happen. Cats will live with dogs, the universe may implode, and worse yet, you’ve lost your document.
Now if instead of your dot, you see an “X”, you are good to go. Document saved. You are free to close and move on.