FB18171249: Button click cancellation in modal dialogs is broken

[lemonmojo]

Submission Date

2025-06-18

Status

Open

Area

AppKit

Operating System Version

macOS 26 Beta 1

Type

Incorrect/Unexpected Behavior

Description

Button click cancellation (by dragging the mouse cursor off a button and releasing it outside the bounds of the button) is broken in modal dialogs in macOS 26 Beta 1.

This seems to only affect dialogs that are run modally. I cannot reproduce it with buttons that appear in windows that are not presented modally.

The easiest way to reproduce it is by spawning an NSAlert using the runModal function.

Here's a simple Swift AppKit example:

import Cocoa

@main
class AppDelegate: NSObject, NSApplicationDelegate {
    func applicationDidFinishLaunching(_ aNotification: Notification) {
        let alert = NSAlert()
        alert.messageText = "macOS 26 Beta 1 Button Click Cancellation in Modal Dialogs"
        alert.informativeText = "Button click cancellation in modal dialogs is broken."
        alert.addButton(withTitle: "OK")
        alert.runModal()
        
        print("After NSAlert.runModal")
    }
}

Actions taken to reproduce the problem:

• Put the mouse cursor over the "OK" button.
• Press the left mouse button and keep it held down.
• Drag the mouse cursor off the "OK" button while keeping it held down.
• Release the mouse button outside the bounds of the "OK" button.

What should happen:

• The button should not respond to the click and the alert should remain visible.

What does happen instead:

• The button responds to the click, the alert is dismissed and "After NSAlert.runModal" is printed to the console.

macOS26_Beta1_ModalDialogButtonClickCancellation.mov

Keywords

button, modal, dialog, cancellation

Prerequisites

• The title follows the format FB<number>: <title>
• I will keep this issue updated with Apple's responses

[malhal]

Interesting, I noticed the same problem with toggle switch on iOS. If toggled left, pressing and dragging it left causes it to toggle to right but it should stay left.