When I first saw this posted over at mozilla links, I really didn’t understand what ‘In-Content Preferences’ was. Turns out it is another feature that Mozilla stole…I mean borrowed from Chrome. However, this is going to be a nice change to the Firefox UI. Currently, when you access the Options (Firefox Button > Options > Options) you get a pop-up window where you can make changes to your Firefox preferences. The downside is you can not do anything else with Firefox until you close the preferences window. Starting with Firefox 15, the preferences “window” will be opening in a new tab. The nice thing about this is you will be able to switch away from this tab, still leaving the tab open.
This feature is available (but not active by default) on the current Firefox 15 Aurora builds. To activate you will need to go into about:config and toggle the setting for browser.preferences.inContent to true. The change should take effect immediately. Firefox 15 will be released around August 28, 2012.