The editor isn't a fixed page with hard-coded boxes. It is a workspace of independent panels: the video player, the chat activity graph, the clip list, the chat log, search, and the TTV clips browser. Each one is its own draggable surface.
Drop a tab on another tab strip to dock as a new tab. Drop it on the edge of a panel to split that area and place the panel there. Drop it in empty space to make it a floating window. The same gesture vocabulary every dockable IDE or DCC tool uses, in your browser.