bug964306 add preview to popup icon

We use two spaces for tabs, and I see this line has four. No biggie, just update to two.

You took this and ran with it, I like that. I also like how you came up with a unique solution, it's making me think. You also did this quickly. Good job.

I'm not really sure if we want to update it live, or have a preview icon. We can try both, and see which one we like best.

One thing that I'm sure about is the live preview is better than what we have.

I propose we land this after the small whitespace fixes.

Then, if pbaisla wants, and we can help you with adding an icon preview instead of the live preview.