Command entry: Point-Of-View (POV) viewport label menu 
Extended Viewports Material Explorer Material (lower) panel Menu bar
The lower Material panel menu bar contains various options for managing materials and the display of the lower panel window.
The choices here are the same as for the upper Scene panel Select menu, except that the choices to control name searching aren’t present.
Most of the choices here are the same as for the upper Scene panel Display Menu, except that the choices about object display aren’t present.
Synchronizes selection of map and sub-material levels in the Scene (upper) and Material (lower) panels. When both this choice and Sync To Material Explorer are on, selecting a material, map, or sub-material in the upper Scene panel displays the entire material tree in the lower Material panel. When Sync To Material Explorer is on but Sync To Material Level is off, selecting a map or sub-material in the upper Scene panel displays only that map or sub-material in the lower Material panel. Default=on.
Opens a Render Map dialog so you can render the selected map.
This choice is unavailable if you’ve selected a material instead of a map.
Opens the Clean MultiMaterial utility so you can remove unused sub-materials..
Opens the Instance Duplicate Maps utility, so you can improve scene and rendering performance by turning duplicate maps into instances.
Opens the Material/Map Browser so you can change the material or map type.
Opens a submenu with one choice, “Display,” that toggles display buttons to the left of the lower panel main window. These buttons mostly correspond to entries on the lower panel Display menu.
