The portion of the view that has been rendered and is available for responsive scrolling.
During responsive scrolling, this property specifies the portion of the view that has been rendered and is ready to scroll. This rectangle always includes the visible portion of the view and may also include nonvisible portions that have been rendered and cached.
Changing the value of this property alerts AppKit that it might need to generate new overdraw content. For example, setting the value to the current visible rectangle forces AppKit to throw away any cached overdraw content and regenerate it during the next idle period. Never assign a rectangle that is smaller than the visible rectangle.