This menu contains commands for setting up and controlling viewports. For ease of use, some of the commands found on this menu also appear on the viewport label menus.
Interface
Undo View Change / Redo View Change
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Viewport Lighting and Shadows 
- Auto Display Selected Lights When on, light from selected lights is automatically displayed in shaded viewports. Default=off.
This option is equivalent to the same option in the Lighting And Shadows tab for viewport configuration: changing the setting here changes the active setting in the preferences dialog, and vice versa.
- Lock Selected Lights Locks the selected lights.
To “lock” a light means that the light will stay on until it is unlocked, whether or not the light casts shadows. When a light is locked, choosing Display Only Selected Lights or Auto Display Selected Lights does not turn it off.
- Unlock Selected Lights Unlocks the selected lights.
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Viewport Background
- Gradient Color (The default for Perspective viewports.) Displays the background as a gradient.
To customize the gradient colors, use the Customize User Interface dialog
Colors panel Viewport Background Gradient Bottom and Viewport Background Gradient Top options. - Solid Color (The default for axonometric viewports.) Displays the background as a solid color.
To customize the solid background color, use the Customize User Interface dialog
Colors panel Viewport Background option. - Environment Background Displays the background specified on the Environment panel.
- Custom Image File Displays an image used for viewports only.
To choose an image file for one or all viewports, use the Viewport Configuration dialog
Background panel. - Configure Viewport Background Opens the Viewport Configuration dialog Background panel.
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Progressive Display (Nitrous viewports): Turns on both progressive display and adaptive degradation.
Adaptive Degradation (legacy viewports)