The active sample slot is displayed with a white border around it.
The sample slot shows a sample object shaded with a material. (By default, the sample object is a sphere.) The sample object is lit by a light source above it and slightly toward the viewer. For the sphere, the highlight is in the upper-left quadrant. The diffuse color shows most clearly above and to the left of the highlight, shading toward the ambient color at the sphere's lower right.