I don't know if this would help for Pixie but it did with Ripley years ago. We had to train him with a water bottle to stop doing things he shouldn't (biting, scratching, chewing and getting on counters). After so many squirts with water it only took shaking the bottle to make him stop. When he started trying to dart out the door I started keeping the water bottle nearby and would shake it every time I was about to go out the door. Pretty soon he got the idea and finally stopped waiting to make a dash.

I've been lucky so far that no other kitty has been a big door darter, with the exception of Rumor and Jazz every once in a while, but if anyone starts that up the water bottle will be back out.