I'm a believer that no matter how well any dog is trained you should always be careful. Especially yorkies/terriers and other high prey driven breeds. You may be able to train her not to bolt out the door or to stay at your side during walks, or to "down!" on command, but if she looks out the door and there is a person across the street, a bird in someone's yard, something interesting out there that triggers her instincts... just expect her to run to it! No one wants to see their beloved pet pummled by a vehicle or attacked by another loose dog.
With smaller dogs I have always picked them up when I have to open the door, or in cases of some dogs just clipped their leash on. But def. training her to "sit", "stay" and "down!" are a must
it will help a lot and a good owner and dog bond will help too, if she is truly bonded with you and trusts you with those commands just about anything is possible especially during bolting away or getting loose.