NSSplitViewItem.CollapseBehavior.default The item uses the default collapsing behavior. Declarationcase `default` See AlsoConstantsNSSplitViewItem.CollapseBehavior.preferResizingSplitViewWithFixedSiblingsNSSplitViewItem.CollapseBehavior.preferResizingSiblingsWithFixedSplitViewNSSplitViewItem.CollapseBehavior.useConstraints