NSPopover失去焦点后，addCursorRect在NSButton上失败

import Cocoa

class ViewController: NSViewController, NSPopoverDelegate {
    var popover: NSPopover!
    var button: NSButton!

    override func viewDidLoad() {
        super.viewDidLoad()
        
        button = NSButton(frame: CGRect(x: 50, y: 50, width: 100, height: 30))
        button.title = "Click Me"
        view.addSubview(button)
        
        popover = NSPopover()
        popover.contentViewController = self
        popover.delegate = self
        
        button.target = self
        button.action = #selector(showPopover(_:))
    }
    
    @objc func showPopover(_ sender: Any) {
        popover.show(relativeTo: button.bounds, of: button, preferredEdge: .maxY)
    }
    
    // NSPopoverDelegate method to handle cursor shape when popover is shown
    func popoverWillShow(_ notification: Notification) {
        button.addCursorRect(button.bounds, cursor: .pointingHand)
    }
    
    // NSPopoverDelegate method to handle cursor shape when popover is hidden
    func popoverDidClose(_ notification: Notification) {
        button.removeCursorRect(button.bounds)
    }
}