Backspace
Delete Selected Light
Enter
Show Properties of selected light
Select a light
Deselect a light
(with light selected)Move selected light
Ctrl
(with light selected)Move selected light up/down


By showing the properties of a light you can edit them. Lights have several properties
Most importantly:

PositionUndocumented feature
ColorChanges the color of a light. Values range from 0 to 1, 0 being no color and 1 being white. If you want normal lights, do NOT put these at 1, but at 0
IntensityThe maximum brightness a light gives. Values range from 0 to 256
RangeThe range a light shines (1 texture tile = 10 range)
Light FalloffThe speed at which the light falls off (use 1 for linear falloff)
Casts ShadowDetermines if this light casts shadows
Max. Light IncrementThe maximum a light should increment a voxel. Values range from 0 to 256

Light's intensity is stretched from the light's origin to the range around it. If you'd map the distance to the light to the intensity, these are some graphs: