Even though web pages can make themselves wider and wider to cannibalize all those 800 pixels of extra space, human beings cannot read sentences with more than 20 words per line. This imposes a hard limit on how wide web pages can be, without hurting legibility, or without cluttering the site with unnecessary extra columns.

The new Browspace has the exact same elements you had seen in Firefox, just re-arranged to use spaces efficiently and intuitively. The bookmarks bar and tabs bar, as well as recent history menu, are now all turned into thumbnails of the web sites, placed in a common area I would call "BrowSpace".