Above the Material Editor sample slots is the menu bar. Below and to the right of the sample slots are buttons and other controls that you use to manage and change maps and materials.
Material Editor tools below and to the right of the sample slots
Material Editor Menu Bar
Reflectance and Transmittance Display
Buttons below the sample slots (the "toolbar"):
Get Material
Put Material to Scene
Assign Material to Selection
Reset Map/Mtl to Default Settings
Make Material Copy
Make Unique
Put to Library
Material ID Channel flyout
Show Shaded/Realistic Material in Viewport flyout
Show End Result
Go to Parent
Go Forward to Sibling
Buttons to the right of the sample slots:
Sample Type flyout
Backlight
Sample Slot Background
Sample UV Tiling flyout
Video Color Check
Make Preview, Play Preview, Save Preview flyout
Material Editor Options
Select By Material
Material/Map Navigator
Controls below the toolbar:
Pick Material From Object (Eyedropper)
Name Field (Materials and Maps)
Type Button (Materials and Maps)