splitView(_:effectiveRect:forDrawnRect:ofDividerAt:)
Allows the split view controller to modify the rectangle where mouse clicks initiate divider dragging.
Declaration
@MainActor func splitView(_ splitView: NSSplitView, effectiveRect proposedEffectiveRect: NSRect, forDrawnRect drawnRect: NSRect, ofDividerAt dividerIndex: Int) -> NSRect