This applies on Ted4 and Fred4.

In the area of graphical user interfaces (GUI), a tabbed document interface (TDI) is one that allows multiple documents to be contained within a single window, using tabs as a navigational widget for switching between sets of documents. It is an interface style most commonly associated with web browsers, web applications, text editors, and preference panes.

GUI tabs are modeled after traditional card tabs inserted in paper files or card indexes (in keeping with the desktop metaphor).

While a stand-alone application typically runs in its own main window, all main tabs "applications" are embedded in the same main window, and each is displayed on its own main tab. Having in mind that you can save in a workspace the list of "applications", the most obvious advantage is that you can open multiple "applications" in a single step and in the same application frame, or you can close them, minimize them or move elsewhere.

For example, while you are working on pages in Fred4, or on articles in Ted4, you can switch to the Shell main tab to retrieve and browse wire or archived images or videos. The pages and articles, being on its own main tab remain exactly where you've left them, and you return to them with a simple click. Moreover, you can manage an edition, by clicking the Editions tab, and then return to your pages on the Pages tab.