Alt-Tabby

A fast, customizable Alt-Tab replacement for Windows, built with AutoHotkey v2. Designed for power users who want responsive window switching with deep integration for tiling window managers like Komorebi.

Features

• Low Latency - Keyboard hooks run in the GUI process for sub-5ms response times
• MRU Ordering - Windows sorted by most-recently-used, matching native Windows behavior
• Komorebi Integration - Workspace-aware filtering and cross-workspace window activation
• Workspace Toggle - Press Ctrl during Alt-Tab to filter by current workspace
• Configurable - GUI-based configuration editor with live preview
• Fullscreen Bypass - Automatically uses native Alt-Tab in fullscreen games
• Process Blacklist - Exclude specific applications from Alt-Tabby
• Window Blacklist - Filter out unwanted windows by title or class

Architecture

Alt-Tabby uses a multi-process architecture for reliability and performance:

+------------------+     +------------------+     +------------------+
|    Launcher      |     |   WindowStore    |     |    Alt-Tab GUI   |
|  (Tray + Spawn)  |---->|    (Server)      |<--->|    (Client)      |
+------------------+     +------------------+     +------------------+
                               ^
                               |
                         +-----+-----+
                         |  Viewer   |
                         | (Debug)   |
                         +-----------+

WindowStore (Server)

The store maintains the authoritative window list with real-time updates from multiple producers:

Producer	Purpose
WinEventHook	Window create/destroy/focus events (primary)
WinEnum	Full window enumeration (on-demand, for Z-order)
MRU_Lite	Focus tracking (fallback if WinEventHook fails)
KomorebiSub	Workspace tracking via komorebi subscription
KomorebiLite	Workspace polling (fallback if subscription fails)
IconPump	Async icon extraction
ProcPump	Process name resolution

Clients connect via named pipe (\\.\pipe\tabby_store_v1) and receive delta updates.

Alt-Tab GUI (Client)

The overlay window with keyboard hooks built-in for minimal latency:

• Intercepts Alt+Tab before Windows sees it
• Requests pre-warmed snapshots on Alt press
• Freezes the window list on first Tab press
• Supports quick-switch (Alt+Tab+release before GUI shows)

Debug Viewer

A diagnostic tool showing the live window list with all fields:

• Toggle between Z-order and MRU sorting
• Filter by current workspace
• Show/hide minimized and cloaked windows
• Double-click to blacklist windows
• Monitor producer health status

Installation

Requirements

• Windows 10/11
• AutoHotkey v2 (for development)
• Optional: Komorebi for workspace features

From Release

1. Download AltTabby.exe from Releases
2. Run AltTabby.exe
3. Right-click the tray icon for options

From Source

git clone https://github.com/cwilliams5/Alt-Tabby.git
cd Alt-Tabby

# Run in development mode
AutoHotkey64.exe src/alt_tabby.ahk

# Or compile
compile.bat

Configuration

Access the configuration editor via:

• Tray icon > Config
• Command line: AltTabby.exe --config

Key settings:

Setting	Default	Description
GraceMs	150	Delay before showing GUI (quick-switch window)
FreezeWindowList	false	Lock list on first Tab press
BypassFullscreen	true	Use native Alt-Tab in fullscreen apps
BypassProcesses	""	Comma-separated process names to bypass

Configuration is stored in config.ini next to the executable.

Usage

Action	Keys
Open Alt-Tab	Alt + Tab
Next window	Tab (while holding Alt)
Previous window	Shift + Tab
Toggle workspace filter	Ctrl (while Alt-Tab is open)
Cancel	Escape
Switch to selected	Release Alt

Documentation

• IPC Protocol - Named pipe message schema
• WindowStore API - Store internals and record fields

Development

Project Structure

src/
  alt_tabby.ahk       # Unified entry point
  gui/                # Alt-Tab overlay
    gui_main.ahk      # Entry, globals, init
    gui_interceptor.ahk # Keyboard hooks
    gui_state.ahk     # State machine
    gui_store.ahk     # Store IPC client
    gui_paint.ahk     # Rendering
  store/              # WindowStore server
    store_server.ahk  # Main process
    windowstore.ahk   # Core API
    winevent_hook.ahk # Window events
    komorebi_sub.ahk  # Komorebi integration
  viewer/             # Debug viewer
  shared/             # IPC, JSON, config
tests/
  run_tests.ahk       # Test orchestrator
  gui_tests.ahk       # State machine tests

Running Tests

# Unit and integration tests
AutoHotkey64.exe tests/run_tests.ahk --live

# GUI state machine tests
AutoHotkey64.exe tests/gui_tests.ahk

Compiling

compile.bat
# Output: release/AltTabby.exe

License

MIT

Acknowledgments

• Komorebi - Tiling window manager for Windows
• AutoHotkey - Scripting language for Windows automation