Multiscreen systems, notably UNIX platforms using -Xinerama, have no way to distinguish between GraphicsDevices which represent actual physical display devices, and GraphicsDevices for a "virtual" display spanning several physical devices.  Client systems such as Java3D need to be able to make this distinction.  java.awt.GraphicsDevice enhancements akin to the following would remedy this situation:

/**
 * Returns true if this GraphicsDevice represents physical display hardware,
 * false if it represents a "virtual" display.
 */
public boolean isPhysicalDevice();

/**
 * This method returns an array of the physical GraphicsDevices spanned by
 * a virtual display.  If called on a GraphicsDevice which is itself a
 * physical display, rather than a virtual display, this method simply returns
 * a single-element array with a reference to itself.
 */
public GraphicsDevice[] getPhyicalScreens()


One is issue is how these methods should be implemented for printers.