The Light source editor dialog is used to specify the location, type, intensity, and color of up to eight light sources. By default, a single directional light source exists, located at the viewer, pointing in the direction of the view. This light source is always Light at viewer and cannot have its type modified.
Light sources are defined in the model coordinate system and are shared among all viewports, that is, if a light source is defined, it is defined for all viewports.