UPDATE: 2014.1 - The admin's shell is now fluid (vs. fixed widths at various break points)

The admin's shell is now fluid (vs. fixed widths at various break points).

Normal pages still have a max width so that there will be stars on the right. Grid pages and a few others (theme html and css editors) have no max and will fill the entire screen (minus mebar and navigation)

At very low resolutions the navigation and mebar are hidden offscreen and replaced with a "hamburger" menu.