This window appears by default the first time you launch Mudbox, and directs your attention to the new features in the Mudbox interface that are highlighted in green. Turn off the Show this window at startup option if you don't want this window to appear.
See also Change the display of What's New highlighting.
Except where otherwise noted, this work is licensed under a Creative Commons Attribution-NonCommercial-ShareAlike 3.0 Unported License