AppKit Modernization

Bringing an existing AppKit app up to modern macOS conventions: input handling without mouseDown overrides, keyboard navigation, graceful quitting 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
• Fixing Full Keyboard Navigation that skips views or follows a stale key view loop
• 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 and interactive Liquid Glass

Example Prompts

Questions you can ask your assistant that will draw from this skill:

• "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, and NSTextSelectionManager on macOS 27)
• Control events in AppKit: addTarget(_:action:for:) works back to macOS 11, and the semantic cases (.valueChanged, .primaryActionTriggered, .trackingRepeated, .menuActionTriggered) 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: setting preventsApplicationTerminationWhenModal to false on sheets that don't need intervention
• The full three-step NSWindowRestoration workflow with encode and decode examples, restoring UI state rather than data

macOS 27 Look and Feel

• The automatic Liquid Glass refinements, and interactive glass (effectIsInteractive)
• Concentric corner configuration (cornerConfiguration, NSViewCornerRadius.containerConcentric)
• Semantic roles for segmented controls and toolbar item groups

Documentation Scope

This page documents the appkit-modernization skill (in the axiom-macos suite), which your assistant uses when you modernize AppKit input handling, state restoration, and your app's macOS 27 look and feel.

Related

• touch – Touch input on touch-display Macs and Sidecar, which builds on this skill's input map
• 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 counterpart to this skill

Resources

WWDC: 2026-289

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