You have to be really careful opening doors. He's bolted a few times. He's only ever made it to the end of the patio before he stops like the grass is made of lava. It makes it pretty easy to walk to him and catch him. Still, I don't want to risk him ever getting brave enough to actually go so I always shoo him away before I open the door.
He loves to reach up at the things he wants. He realizes doors are the way outside so trims to all of our exterior doors are covered in scratch marks. This is how he learned to open the door between the kitchen and the garage. That door gets locked now. We just leave the key in the chamber on the other side.
Smart little butthead.