DockAltTab
Window previews for the macOS Dock, built directly on top of AltTab.
Hover a Dock icon and its windows pop up right above it; the AltTab switcher (⌥⇥ by default) is still there too.
This used to be two apps: a DockAltTab companion that drove a "scriptable" fork of AltTab through AppleScript. This repository merges them — the DockAltTab behaviour now lives inside the AltTab codebase (see src/DockAltTab), so there is no companion app and no AppleScript round-trip. Everything AltTab does (the switcher, the settings window, Sparkle updates, …) is still included.
Website:
What it does
- Dock hover previews — hover any Dock app icon to see its windows, positioned and clipped relative to the icon (magnification- and edge-aware).
- Thumbnail previews — hover a window thumbnail to get a large preview of that window; the delay is configurable.
- No unwanted Space switching — clicking a Dock icon in the click-driven modes is handled by DockAltTab, so activating an app whose windows live on another Space unhides it first and only activates once it is visible, instead of triggering a Space swoosh.
- The full AltTab switcher and settings remain available.
Modes
DockAltTab has three interaction styles, selectable in its preferences:
| Mode | Hover a Dock icon | Left-click a Dock icon | Middle-click a Dock icon | | --- | --- | --- | --- | | MacOS | show previews | native Dock behaviour | native Dock behaviour | | Windows | show previews | non-frontmost app → activate it; frontmost app → hide it | — | | Ubuntu | — | non-frontmost app → activate it; frontmost app with ≥2 windows → toggle previews; otherwise → hide it | show previews (if the app has ≥1 window) |
In every mode, a click that DockAltTab acts on is swallowed, so the native Dock cannot also fire a Space switch.
Preferences
The menu-bar menu has a DockAltTab item (first in the list) that opens the DockAltTab Preferences window. It contains the Preview Settings:
- Mode — MacOS / Windows / Ubuntu
- Show Delay — delay before previews appear when hovering an icon
- Hide Delay — delay before previews disappear when leaving
- Thumbnail Preview Delay — delay before a hovered thumbnail expands
- Enable Thumbnail Previews
- Reposition preview after dock magnification — follow the icon while the Dock magnification animation settles
- Preview Distance — gap between the previews and the Dock
- Keep dock showing during previews — keep an auto-hiding Dock visible while previewing
Permissions
- Accessibility — required (global event taps + Accessibility queries of the Dock and windows).
- Screen Recording — required for window thumbnails.
Install / build
Build from source with Xcode (the workspace includes the CocoaPods dependencies):
# from the repository root
xcodebuild -workspace alt-tab-macos.xcworkspace -scheme Debug -configuration Debug buildOr open alt-tab-macos.xcworkspace in Xcode and run the Debug scheme. The product is DockAltTab.app.
CocoaPods are vendored under Pods/, so a separate pod install is normally not required.
Scripting
The app is scriptable (this comes from the scriptable AltTab fork). The dictionary is in DockAltTab.sdef.
Basic commands
- hide — hide the overlay/UI.
- show — show all app windows (the regular AltTab shortcut).
- showApp — show a specific app's windows (ignores the blacklist).
appBID — bundle identifier of the app.
- x / y (optional) — position of the Dock icon; resets on hide.
- dockPos (optional) — bottom / left / right, helps position/clip the previews.
- trigger — go to the next window without showing the overlay.
Miscellaneous commands
- countWindows (
appBID) — number of windows for an app, across all Spaces. - countWindowsCurrentSpace (
appBID) — number of windows for an app in the current Space. - countMinimizedWindowsCurrentSpace (
appBID) — number of minimized windows for an app in the current Space. - countWindowStats (
appBID) / countAllWindowStats — window-count records. - deminimizeFirstMinimizedWindowFromCurrentSpace (
appBID) — deminimize the app's first window minimized on the current Space. - keyState (
key) — whether a key is currently pressed. - appSetting (
named) — read a setting used forshowApppreviews (appsToShow,showHiddenWindows,showFullscreenWindows,showMinimizedWindows,spacesToShow,screensToShow,showTabsAsWindows). - thumbnailPreview — show the large preview of the selected window.
- repositionThumbnails (
{x, y}) — reposition the preview panel.
Example:
tell application "DockAltTab" to showApp appBID "com.apple.Safari"
tell application "DockAltTab" to showApp appBID "com.apple.Safari" x 0 y 0 dockPos "bottom"
tell application "DockAltTab" to hideInternally, DockAltTab no longer needs these commands — it calls the same code directly — but they are kept for automation.
Notes / differences
- On launch, if the Dock's
showhiddenpreference is off, DockAltTab enables it and restarts the Dock once (translucent icons for hidden apps). - Some apps' windows are ignored by personal preference, e.g. BetterTouchTool "pinned"/floating windows and Screenhint floating windows.
- Preview button order: Exit first, Quit last.
- Fading is faster for DockAltTab previews (111 ms) than for regular previews (333 ms).
- Window controls auto-reopen after closing a window, so repeated clicks keep working.
Credits
DockAltTab is built on AltTab by Louis Pontoise and contributors, and on the "scriptable" fork by steventheworker. Both are licensed under GPL-3.0; see LICENCE.md.
Sister app: Dock Exposé.