Honestly, if you started getting up and walking away every time I came to your cube, I'd be there 3 times a day and half of the other people in the office would be in on it and find it hilarious and you'd probably end up in the cupboard crying and hand in your notice.
Seriously just say "please don't touch my screen" instead of this hilarious behaviour.
I'd just quit, simple as that. If my boss wanted me to stay, he'd make sure you stopped or left. I'm an experienced javascripter in Silicon Valley. Finding a job is not a problem, in this or any economy, and nothing's worth working in a hostile environment. If you were working for me, you'd be fired on the spot for such behavior.
In a professional environment, blatant disrespect should not be tolerated. I'm pretty sure my feelings on this matter are not unusual.
The "don't touch my screen" thing is fine by me, but that mardy shit can fuck off, either say it or get out.