For the majority of Dofus's lifespan, playing the game meant dealing with a specific UI quirk. When you launched the game, you opened the Dofus client window. Inside that window, the actual game was rendered. If you played multiple accounts (a practice known as "muleing" or multi-accounting), you didn't use tabs; you had multiple instances of the client open.

: A third-party utility that physically groups separate Dofus windows into a single tabbed interface, similar to a web browser. Native Windows Shortcuts & Optimization

If you cannot pay for Groupy or AquaSnap:

In recent years, Ankama began the monumental task of migrating Dofus from Flash/Adobe Air to the Unity engine. This wasn't just a graphical update; it fundamentally changed how the game client interacts with your operating system. With the Unity client, the "window within a window" concept began to fade, paving the way for more modern window management features.