Some features in Firefox 3.6 like Ctrl Tab previews, Taskbar previews in Windows 7 and some other features are disabled by default though we can enable these features manually through about :config, Secrets of Firefox extension automatically enables defaultly disabled features in Firefox 3.6.
Secrets of Firefox enables following features in Firefox 3.6
- Taskbar Previews [Windows 7]
- Tab Previews [Ctrl +Tab]
- Tab Previews menu button (far right in the tab bar)
- Open links to right of the current tab
You can always enable any feature if not enabled or shown not selected in the settings of Secrets of Firefox through options of Secrets of Firefox add-on.