Nscolorpanel - strange

I have strange things happening when attempting to create a NSColorPanel in Swift

here is a very MINIMAL test project

import Cocoa

class AppDelegate: NSObject, NSApplicationDelegate {
	func applicationDidFinishLaunching(_ aNotification: Notification) {
		let cp = NSColorPanel.shared
		cp.isContinuous = true
		cp.showsAlpha   = false
		cp.color = NSColor.green

	func applicationWillTerminate(_ aNotification: Notification) {
		// Insert code here to tear down your application

	func applicationSupportsSecureRestorableState(_ app: NSApplication) -> Bool {
		return true

	@objc private func colorDidChange(_ sender: Any?) {
		if let cp = sender as? NSColorPanel {


this is the display I get

anytime I change the code above (like setting a new default color)… the next run has MORE boxes at the bottom. It just gets taller and taller… I have spent all day looking for anything that might lend a clue.

Note : if you create a project and add this code… it will “probably” be ok… until you change something