Yeah, that is actually the Attribute editor replacing the Channel box. If you look directly above the box on the right side there are three little buttons, the one on the far right toggles the Channel box. You probably just want to change the option to make it open in a new window like vladimirjp said, but a helpful tip is that you can also toggle it with control+a. So if the attribute editor opens in place of the channel box, you can just hit that and it will go away again.