Ambient Indicators are an interesting and subtle feature that’s built into OS X. Since I just learned about them after over a year of using a Mac, I’d be willing to bet that not many of my fellow OS X users know about them either. The next time you have an open window, check out the close button. When an open file hasn’t been saved in its current state, the close button goes from solid red to red with a dark dot in the center. Though it might not do much, if you look out for it, you’ll never be surprised by the “Do you want to save?” pop up box ever again.