I must agree with CyberShot. This wouldn't work, and it's hard to stop users who just copy the code into their own website. Many would get away with it, without anyone noticing. Wouldn't it be better with a marcetplace for small regular applications?
If there is no live preview they can’t steal it 
Plus, if they come out with this, apps and mods (for mybb, wordpress, etc) are a must!