The rectangle within the positioning view relative to which the popover should be positioned.
- macOS 10.7+
Popovers are positioned relative to a positioning view and are automatically moved when the location or size of the positioning view changes.
Sometimes it is desirable to position popovers relative to a rectangle within the positioning view. In this case, you must update the
positioning property whenever this rectangle changes.
This property is exposed as a read-only binding.