If you go to Tools|3do Hierarchy, then hit "Edit Mesh XYZ", "Extra Mode" will be activated (you MUST do this first). Extra Mode is the 3do Mesh XYZ editing mode.
Maybe this was added to prevent you from needing to go to the menu every time you wanted to edit Mesh offsets? So after you exited Mesh Offset Editing you just hit the button and it puts you back in that mode.
Maybe this was added to prevent you from needing to go to the menu every time you wanted to edit Mesh offsets? So after you exited Mesh Offset Editing you just hit the button and it puts you back in that mode.
May the mass times acceleration be with you.

