The area inside the window that is for non-obscured content, in window coordinates.
- macOS 10.10+
Typically, the area represented by this property is the same as the frame of the
content. However, for windows with
NSFull set, there needs to be a way to determine the portion that is not under the toolbar. The
content property contains the portion of the layout that is not obscured under the toolbar. This property is KVO compliant.