The upper Scene panel of the Material Explorer has a toolbar with various search, selection, and other controls.
The toolbar actually consists of three smaller toolbars: Find, Selection, and Tools. You can toggle the display of these smaller toolbars by using the Toolbars options on the Customize menu.
Enter text in this field to search for that text in the Name column. As you type, the Material Explorer highlights materials or objects whose name matches the search string.
If Sync to Material Explorer is on, the Material (lower) panel also displays the first material that is found. If the Material Explorer finds an object rather than a material, the Material (lower) panel shows the material that is applied to that object.
Some options on the Select menu control how the Explorer performs the search.
Some of these buttons correspond to choices on the Select menu.
Selects all materials in the scene.
Selects all maps in the scene.
Selects all entries in the scene.
Deselects all entries in the scene.
Inverts the current selection: all selected entries become deselected, and all entries not selected become selected.
When on, prevents you from editing cells in the Explorer: clicking a cell has no effect, other than to highlight and select the row it is in. Default=off.
When on, synchronizes selections in the Material (lower) panel with the Scene (upper) panel. When off, changing the selection in the Scene panel doesn’t change the Material panel, which continues to show the last material you selected before turning off Sync To Material Explorer. Default=on.
When on, the lower Material panel always shows the full hierarchy of the material highlighted in the upper Scene panel, even if only a component of the material is highlighted. When off, the lower Material panel shows only the hierarchy of the individual material component that is highlighted in the upper Scene panel. Default=on.