How to let Appkit Scrollview get under sidebar or inspctor?

If I use a SwiftUI Scrollview and scroll horizontally, for example, the scroll content goes underneath the inspector or sidebar views on macOS 26 (probably on older versions as well)

But by default, the AppKit scrollviews don't exhibit this behaviour. How do I adapt this to match SwiftUI behavior?

Setting the NSSplitViewItem used for the content view’s automaticallyAdjustsSafeAreaInsets property to true will do this.

How to let Appkit Scrollview get under sidebar or inspctor?
 
 
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