TextField in popover. "This would eventually crash when the view is freed" - macos

Question

I have written an app to display timezones in a NSStatusBar popover. All good so far but when I add a second popover from a button inside the original popover view and include a TextField I start getting problems.
The TextField shows as having focus but it refuses input. If I toggle in and out of the second popover then I get a crash.
...as the first responder for window <_NSPopoverWindow: 0x7fb9c1807bb0>, but it is in a different window ((null))! This would eventually crash when the view is freed. The first responder will be set to nil.
I'm assuming these are related.
I have extracted just the NSStatus bar setup and the two popover views and it is fully repeatable in this toy instance. I use an EventMonitor to catch a click outside of the popover to close it. I don't think that is relevant but I have included it in the toy app for completeness
AppDelegate.swift
import Cocoa
import SwiftUI
#NSApplicationMain
class AppDelegate: NSObject, NSApplicationDelegate {
var popover: NSPopover!
var statusBarItem: NSStatusItem!
var eventMonitor: EventMonitor?
var contentView = ContentView()
func applicationDidFinishLaunching(_ aNotification: Notification) {
// Create the popover
let popover = NSPopover()
popover.behavior = .transient
popover.contentViewController = NSHostingController(rootView: contentView)
self.popover = popover
// Create the status item
self.statusBarItem = NSStatusBar.system.statusItem(withLength: CGFloat(NSStatusItem.variableLength))
if let button = self.statusBarItem.button {
button.image = NSImage(named: "Icon")
button.action = #selector(togglePopover(_:))
}
eventMonitor = EventMonitor(mask: [.leftMouseDown, .rightMouseDown]) { [unowned self] event in
if self.popover.isShown {
closePopover(event)
}
}
eventMonitor?.start()
NSApp.activate(ignoringOtherApps: true)
}
#objc func togglePopover(_ sender: AnyObject?) {
if popover.isShown {
closePopover(sender)
} else {
showPopover(sender)
}
}
func showPopover(_ sender: AnyObject?) {
if let button = statusBarItem.button {
popover.show(relativeTo: button.bounds, of: button, preferredEdge: NSRectEdge.minY)
self.popover.contentViewController?.view.window?.becomeKey()
}
eventMonitor?.start()
}
func closePopover(_ sender: AnyObject?) {
popover.performClose(sender)
eventMonitor?.stop()
}
}
open class EventMonitor {
fileprivate var monitor: AnyObject?
fileprivate let mask: NSEvent.EventTypeMask
fileprivate let handler: (NSEvent?) -> ()
public init(mask: NSEvent.EventTypeMask, handler: #escaping (NSEvent?) -> ()) {
self.mask = mask
self.handler = handler
}
deinit {
stop()
}
open func start() {
monitor = NSEvent.addGlobalMonitorForEvents(matching: mask, handler: handler) as AnyObject?
}
open func stop() {
if monitor != nil {
NSEvent.removeMonitor(monitor!)
monitor = nil
}
}
}
ContentView.swift
import SwiftUI
struct ContentView: View {
#State private var showingPopover = false
#State var value: String = "Initial Value"
var body: some View {
VStack {
Button {
showingPopover = true
} label: {
Image(systemName: "globe")
.imageScale(.large)
.foregroundColor(.accentColor)
}
.popover(isPresented: $showingPopover) {
EditView(value: $value)
}
Text("Hello, world!")
}
.padding()
}
}
struct EditView: View {
#Binding var value: String
var body: some View {
VStack {
TextField("Location ", text: $value) // the location as a string
.multilineTextAlignment(.center)
.lineLimit(1)
.onSubmit {
print("value submit \(value)")
}
}
.padding()
.frame(width:200, height: 50)
}
}
I've searched for information and found references to similar problems with windowed applications and needing to click in the 'window' before clicking in the TextField but that doesn't seem to do anything in this context
I'm building on MacOS 12.6.2 with Target set for 12.0