AppKit Modernization

Guidance for bringing an existing AppKit app up to modern macOS conventions: input handling without mouseDown overrides, keyboard navigation, graceful quit and state restoration, and the macOS 27 look-and-feel.

When to Use

Use this skill when you're:

• Replacing mouseDown overrides used for selection, context menus, drag-and-drop, or text selection
• Reacting to control interactions with control events instead of tracking loops
• Showing custom windows from a menu bar status item (expanded interface sessions)
• Making your app quit gracefully during system restarts and restore its windows on relaunch
• Adopting the macOS 27 look: concentric corners, interactive Liquid Glass
• Handling touch input on the Mac (touch scrolling, pull-to-refresh)

Example Prompts

• "How do I modernize my AppKit app's mouseDown handling?"
• "My status item shows a custom window — how do I handle keyboard focus?"
• "My app blocks the overnight software update restart"
• "How do I restore my windows after relaunch with NSWindowRestoration?"
• "How do I make my view's corners concentric with the window?"
• "Are UIControl-style control events available in AppKit?"

What This Skill Provides

Modern Input

• A replacement map for common mouseDown overrides (selection observation, context-menu APIs, modern dragging delegates, NSTextSelectionManager on macOS 27)
• Control events in AppKit — target/action back-deploys to macOS 11; the semantic cases (.valueChanged, .primaryActionTriggered) are new in macOS 27
• The overlapping-sibling hit-testing gotcha and the hitTest fall-through fix

Keyboard Navigation and Status Items

• Key view loop maintenance with autorecalculatesKeyViewLoop
• Expanded interface sessions for status items that show custom windows (macOS 27)

Continuity

• Graceful termination (preventsApplicationTerminationWhenModal)
• The full three-step NSWindowRestoration workflow with encode/decode examples

macOS 27 Look and Feel

• Automatic Liquid Glass refinements, interactive glass (effectIsInteractive)
• Concentric corner configuration (cornerConfiguration, NSViewCornerRadius.containerConcentric)
• The touch-input SDK surface (touch scrolling, NSRefreshController pull-to-refresh)

Documentation Scope

This page documents the appkit-modernization skill in the axiom-macos suite. The skill file contains comprehensive guidance Claude uses when answering your questions about modernizing AppKit input handling, restoration, and the macOS 27 look-and-feel.

For SwiftUI hosting — Use appkit-interop when the modernization step is adopting SwiftUI itself.

Related

• appkit-interop – hosting SwiftUI in AppKit (observation tracking, NSHostingMenu, SwiftUI scenes from an app delegate)
• windows – scene types, window lifecycle, and document apps
• menus-and-commands – menu bar and command patterns
• uikit-modernization – the UIKit sibling skill

Resources

WWDC: 2026-289

Docs: /appkit/nscontrol/events, /appkit/nswindowrestoration, /appkit/nsviewcornerconfiguration