The tab area is the portion of the graphical user interface that contains the browsers, utilities, and other functionality not shown in the panel area.  The tab area can be moved to either the left or right side of the graphics area, or both, or it can be hidden completely.  To maximize available space, multiple features (browsers and utilities, for example) are organized onto tabs; click a tab heading to bring it to the forefront.

Browsers that are displayed in the tab area by default in the framework include the Session browser and the Model browser. Other browsers that can be displayed on or off via the View menu are the Parameters browser, the Process Manager, Library Manager, Solver browser, Connector browser, Mask browser, Entity State browser, and the Utilities menu.

Turn the tab area sidebars on or off by selecting Left, Right, Expand Both, or Collapse Both from the View menu > Tab Area menu.

The Media browser displays the files loaded in your current session in a tree structure.

Media Browser