When I open a tamed horse's GUI and moved my mouse around the screen, the horse's GUI head follows my mouse movements, but then the real horse outside the GUI moves his head as well.

Put the summary of the bug you're having here

What I expected to happen was that the horse wouldn't move at all but his head and body did.

*What actually happened was that the horse's body and head moved when I moved my mouse when I had the GUI open. When I move my mouse vertically, the horse's head looks like it's shaking it's head. When I move the mouse horizontally, it moves the horse's body back and forth.

Steps to Reproduce:
1. Tame a horse and open it's GUI.
2. Move your mouse vertically and horizontally to see if the horse's head and/or body moves.