Here is a sample program to demonstrate the problem. Using Xcode, create a new document project using interface: xib, language: swift Once that is done, delete Document.xib, go into Document.swift and add the following method: override func makeWindowControllers() { let controller = MyWC(document: self) addWindowController(controller) controller.showWindow(self) controller.window?.makeFirstResponder(nil) } Then make a new Swift file named MyWC.swift with this content: import AppKit class MyWC: NSWindowController { init(document: Document) { let window = NSWindow( contentRect: NSRect(x: 0.0, y: 100.0, width: 700.0, height: 500.0), styleMask: [.titled, .closable, .miniaturizable, .resizable], backing: .buffered, defer: false ) super.init(window: window) window.minSize = NSSize(width: 200, height: 200) let myScrollView = NSScrollView() let contentView = NSView(frame: NSRect(x: 0.0, y: 0.0, width: 800.0, height: 600.0)) let clipView = NSClipView(frame: myScrollView.contentView.frame) clipView.backgroundColor = NSColor.blue clipView.drawsBackground = true myScrollView.clipsToBounds = true myScrollView.contentView = clipView myScrollView.documentView = contentView myScrollView.hasHorizontalRuler = true myScrollView.hasVerticalRuler = true myScrollView.rulersVisible = true myScrollView.hasVerticalScroller = true myScrollView.hasHorizontalScroller = true myScrollView.autohidesScrollers = false myScrollView.scrollerStyle = .legacy contentView.wantsLayer = true contentView.layer!.backgroundColor = NSColor.red.cgColor window.contentView = myScrollView } required init?(coder: NSCoder) { fatalError("init(coder:) has not been implemented") } } Build and run the project. Notice that the red color "shows through" the scroll bars. If you expand the window, the blue color of the NSClipView also shows through the scroll bars. I think this is how it is supposed to be. Now edit the MyWC class to set myScrollView.rulersVisible = false And then run it again. This time, the red color of contentView does not show through the scroll bars. Instead the scroll bars are blue, showing the clipView background color. And the lower right corner between the scrollbars is white. To me, this seems to be wrong. First, rulers being invisible shouldn't cause the scrollbars to pick up a different background color and second, the lower right corner certainly shouldn't be white.