Yosemite Full Screen problem :(
People hate Yosemite. But I don’t know why. I like Yosemite more than Mavericks. But Yosemite has a problem with Maximize button. (Zoom) As you click Zoom or maximize button it will go to full-screen mode.
To avoid this press zoom while you are pressing
If you want to maximize Chrome click zoom while you are pressing
Option + Shift