NSOutlineView - How to remove the expand/collapse toggle

Question

I have a NSOutlive view that I would like to remove the toggle from some rows. The Zones and Assets rows are group items (header rows) and should not be collapsable. The problem is that is I answer NO to - (BOOL)outlineView:(NSOutlineView *)outlineView isItemExpandable:(id)item for these items, the toggles do go away, but then I can't programmatically expand then either.

Is there any way to remove the toggle from specific rows?

Answer 1

This apparently is by design and expected behavior (don't ask why, I have no idea). See also this thread in the developer forums: https://devforums.apple.com/message/643148#643148

The problem seems to appear when you turn of the outline cells by returning NO in outlineView:shouldShowOutlineCellForItem:.