The amount of the document view kept visible when scrolling vertically page by page.
- macOS 10.0+
The value of this property is the amount of the document view kept visible when scrolling vertically page by page, expressed in the content view’s coordinate system. This value is used when the user clicks the scroll arrows on the vertical scroll bar while holding down the Option key.
This amount expresses the context that remains when the receiver scrolls by one page, allowing the user to orient to the new display. It differs from the line scroll amount, which indicates how far the document view moves. The page scroll amount is the amount common to the content view before and after the document view is scrolled by one page. Thus, setting the page scroll amount to
0 implies that the entire visible portion of the document view is replaced when a page scroll occurs.