NSOutlineView background scrolls with contents

Question

My application has a NSOutlineView that was initially configured as a source list, because source lists are prettier. However, I decided that I'd rather have the normal tree behavior, so I switched the highlight mode from "Source List" to "Regular". Now the "Show" buttons on the right of top-level cells are gone in favor of familiar triangles to the left, but an unexpected issue arose: it seems that the background scrolls with the contents of the view.

The issue disappears if I select "Source List" again in the Highlight setting, but I'd rather have just the background and not the source list behavior.

How can I fix that? I didn't write a single line of that background's code.

Answer 1

I've seen this kind of error before. The background can become messy when switching back from SourceList highlighting. I usually just remove the outline, drags in a new one and set DataSource and Delegates (+ Class) again.