appearance
The appearance of the popover.
Declaration
var appearance: NSAppearance? { get set }Discussion
If no appearance is specified, the popover’s effective appearance defaults to vibrantLight.
In apps that run in macOS 10.10 and later, the previous property type of NSPopover.Appearance is deprecated. In apps that run in OS X v10.9 and earlier, the aqua appearance is automatically set on popover content.