Keys for group attributes.
A key for the range of a group. The associated value is an NSValue object. This is required if the view uses grouping
A key for the background color of a group. The associated value is an NSColor object. This color is used only for the bezel style.
A key for the title of a group. The associated value is an NSString object. This string is used for the disclosure style only.
A key for the style of a group. The associated value is one of the constants defined in Group Style Attributes.
A key for the header layer of the group. The associated value is a CALayer.