fillColor
A key that contains the behavior to use when filling the empty space around the image.
Declaration
static let fillColor: NSWorkspace.DesktopImageOptionKeyDiscussion
The value is the NSColor object to use when filling any empty space around the image. If you don’t specify this key, the workspace object uses a default color. Currently, the system supports only colors that use or can be converted to use the calibratedRGB color space. The system also ignores any alpha value in the color you specify.