Monitor Glue

Your windows go back where they belong when you plug your monitor back in.

You work from home on one monitor and from the office on another. Every time you unplug, macOS piles every window onto the laptop screen. Plug back in, and nothing goes back — macOS only half-remembers the last display you used. So you drag and resize the same windows, every morning.

Monitor Glue remembers where each window lived, separately for each monitor you use, and puts them back — right monitor, right position, right size — the moment you reconnect.

• Remembers per monitor. Home and office layouts are kept apart and never overwrite each other.
• Remembers the laptop screen too. Unplug and your windows go back to where you had them on the built-in display, not wherever macOS dropped them.
• Restores automatically when a monitor connects, when you open the lid, when the Mac wakes, and when you unlock. If you plug in at the lock screen, it waits and places everything the moment you unlock.
• Respects your changes. Resize a window on the monitor and that becomes its new place. Drag a window to the laptop screen and it stays there — it won't be yanked back.
• Copes with stubborn apps. Some apps refuse certain sizes (Slack has a minimum width); Monitor Glue takes what the app allows instead of fighting it.
• Stays out of the way. A menu-bar app with no Dock icon. A manager window shows every remembered monitor, app and window, and lets you forget any of them. Pick the menu-bar icon that stands out in your menu bar: a glue bottle, a pinned window, or a monitor.

With Homebrew:

brew install --cask erango/tap/monitor-glue

Or download MonitorGlue.zip from the latest release, unzip it, and drag MonitorGlue.app to your Applications folder.

Then open it and grant Accessibility access when asked (System Settings → Privacy & Security → Accessibility). This is the only permission it needs.

Requires macOS 14 Sonoma or later. The app is signed with a Developer ID and notarized by Apple, and keeps itself up to date: choose Check for Updates… in the menu, or let it check automatically.

No analytics, no accounts, and no data leaves your Mac. The only network request is the update check: Monitor Glue asks GitHub whether a newer version exists. It asks your permission before checking automatically, sends no information about your system, and you can switch it off in the menu at any time. Accessibility is used to read and set the position and size of other apps' windows — never their contents. Everything else stays on your Mac:

• Monitors are identified by their hardware UUID, not their macOS display ID (which changes on every reconnect). The set of attached external displays forms the key a layout is saved under — so a home monitor and an office monitor never share a layout. With no monitor attached, the built-in display gets a layout of its own.
• Positions are stored relative to the monitor's own origin. macOS often brings a display back at a different place in its arrangement; relative coordinates still land correctly.
• Windows are read and moved with the Accessibility API, matched back to saved entries by title, then by position in the app's window list.
• Restores retry for up to three minutes, quickly at first. Right after a wake, apps can be unresponsive to Accessibility for a while, and some apps are still relaunching.
• Why it isn't on the Mac App Store: App Store apps must run in the App Sandbox, and the sandbox hides other apps' windows from the Accessibility API. We tested it: the sandboxed build was told it was trusted and then saw zero windows.

• Nothing is restored: check Accessibility is on for Monitor Glue. If it looks on but the app still asks for access, reset it and grant again: tccutil reset Accessibility com.erango.monitorglue
• Something behaved oddly: choose Report a Bug… in the menu. It opens a GitHub issue with your setup filled in and shows the log in Finder, ready to attach. The log records every monitor change and, for each restore, which window matched which saved entry and the frame it got — skim it first, since it includes window titles.

Needs Swift 5.9+ (the Xcode Command Line Tools are enough).

./Scripts/make_cert.sh    # once: a stable local signing identity (see below)
./Scripts/bundle.sh       # builds dist/MonitorGlue.app
open dist/MonitorGlue.app

An ad-hoc-signed build gets a new code hash every time it's rebuilt, and macOS then quietly drops its Accessibility permission. make_cert.sh creates a self-signed identity so local rebuilds keep the permission.

CONFIG=debug ./Scripts/bundle.sh builds into dist/debug/ with a development harness compiled in (MG_PREVIEW=menu, manager, diag, and friends — see DebugPreview.swift). Release builds leave all of it out.

Issues and pull requests are welcome — especially reports of apps or monitor setups that don't restore correctly. Include the log and your macOS version.

Monitor Glue is free and MIT-licensed. If it saves you a few minutes every morning, buy me a coffee ☕

Another way to help, which costs nothing: a like on AlternativeTo helps other people with the same problem find it.

Made by @erango.