Now Good Rated 4 out of 5 stars

All we need. Maybe one other idea ;) Quick cycling through a set of predefined window sizes? A few I think of: mobile phones are 1280x720 or 1920x1080 or 800x600. Alt-End or for Landscapes and Alt-Home for portrait or something?

Edt: installed it. But your display does not update height. I use "1280x768" in top right corner. (dont need the "px" .. that I know;) )

Height? Rated 4 out of 5 stars

Great.. and works (Ubuntu 13.04) :)

But... Responsive design is also about height... at times it is needed to see what fits and not. So.... Why not Alt- up and Alt-Down ? But code is clean and clear... so it took me 10 minutes to add this options and now it is great :)

This review is for a previous version of the add-on (1.3.1-signed). 

That's and great idea! So great that I actually added it to the new version that is now available for download, so you don't have to rely on your own hack anymore. Please consider updating your rating and review if you like the new version.