I currently have a NSView in a NSScrollView.
The NSView is large and I need to scroll to manage the object inside.

I want to draw a static rectangle in the center of the NSView without scrolling.
I want to get the scrolling point (the NSClipPoint?) in the drawRect method of the NSView so that I can draw the rectangle at the last step of drawRect to make it on top.

I have looked through the doc and could only find methods to set the scroll point, not getting it.
How can I get that point?