We have been so lucky (so far anyway) when we open the front door to get something from the car or take out the rubbish smudger just stands on the step and looks outside i think he is a little scared.
we've been hoping that if we dont push him inside or say NO that he won't be interested in running out. I don't know just thought it was worth trying. my mums yorkie makes a run for it every single time the door is opened and she runs straight to the chip shop (don't ask why???)
It is really scary and hopefully Smudger won't make a habit of this.