All-in-One Sidebar (AiOS) is a sidebar control for Firefox, inspired by Opera.

Click on the left edge of your browser window to open the sidebar and get easy access to all your panels. It lets you quickly switch between sidebar panels, view dialog windows such as downloads, add-ons, and more in the sidebar, or view websites in the sidebar. It includes a slide-out button and a toolbar, all of which can be extensively customized. All-In-One Sidebar provides also enhancements for many built-in and extension features and some extra features.

You can set the orientation to left or right, set the minimum, default and maximum width and the behavior on browser startup.

All-in-One Sidebar provides enhancements for many built-in features, which are related to the sidebar.

The options dialog gives you the ability to configure many features, behaviors and the appearance of All-in-One Sidebar.