A team of students at Michigan State University has started a project with Mozilla to move Firefox’s preferences from a dialog window to within a browser tab (content area of the browser). This team will finish the project within 16 weeks.
You must have noticed that the Chrome loads its preferences and settings options in a new tab. You can launch this by visiting the wrench menu > options. While, Firefox loads the options in a separate window.
Now, Mozilla team is working on moving all settings and options windows to the content area of the browser with a new user interface. Although, most of the current preferences windows are created using XUL, and can be loaded in a tab by directly entering the associated Chrome URL in the address bar. For example, the cookies settings can be opened by visiting the URL chrome://browser/content/preferences/cookies.xul .
This UI redesign involves various other elements like Add-on manager etc. Some mockups of the proposed design are available here.