You can open the Lighting Window (see figure) by selecting the Lighting option from the Main Window's Controls menu. The Lighting Window has two modes of operation: edit and preview. When the window is in preview mode, light sources cannot be modified, but they are all visible and illuminate the Lighting Window's test sphere so the cumulative effect of the lights can be observed. When the window is in edit mode, light sources can be modified one at a time. You set light properties using the controls in the Properties panel and you can position lights interactively by moving them around in the lighting panel to the left of the Properties panel.