Yes, it's all one piece of glass, the buttons are covered. I'm not sure I understand your confusion as to how this is possible. It's a piece of glass.. that covers a tiny drawing of a few buttons..![]()
I think the key here is that the "buttons" at the bottom are part of the capacitive surface of the phone (ie: the "touch" area of the phone doesn't have to stop at the edge of the display area).