Discussion: Sidebar tools with greasemonkey

Hey

The new UI left my glitch companion somehow out of space, and I'm thinking about a new layout, as well as full browser support this time.
Looks like I may be able to code something with simplified frameworks like processing or paper.js, but the greasemonkey part still kinda bugs me.

So can anyone tell me how I can add a "sidebar" on the left of the game UI with greasemonkey?
I tried with an iframe linked to a page on my site, but it just appears above the page, without offsetting the content to the right.
Here is my plan in two pics: before - after

It may only works for higher "desktop" resolutions, rather than laptop-like, but still I think embedding an interesting way to go for our apps.