Mine all use the Yorkie Mind Control method to let us know when they need to go out. It's flawed in that it relies on us being intelligent enough to pick up on their Mind Control efforts...needless to say our IQ's are not as high as our Yorkies.
Boo is/was a bolter and we've had to work hard with him to keep him safely inside. He's 100% better at it now, he'll run to the door and lay down on the mat and wait for us to pick him up before we open the door, but I don't think I'll ever 100% trust him to not run out. We are just very viligant when using the front door.