AI-assisted project. This codebase was created with Claude (Anthropic), directed and reviewed by a human author.
A menu-bar app for the Mac that's running your slides or playback. It stops the Mac doing anything clever during the show (going to sleep, popping up notifications, flinging Mission Control onto the projector, letting the cursor wander onto the LED wall), then puts every setting back how you had it.
⌃⌥⌘S starts/ends show mode · ⌃⌥⌘F pauses the cursor fence (to reach a show screen deliberately)
Field proven. It's been used on real events, not just on my desk. On macOS 26.4 I've also run the power, screen saver, hot corner, Mission Control, True Tone and Night Shift guards and every restore path end to end, and the cursor fence (with and without Accessibility), the display lock, Do Not Disturb and appearance pinning on a real two-screen setup. Not tried yet: the display lock with AirPlay, Sidecar or DisplayLink screens. v0.4.0's privacy dots and swipe between Spaces guards haven't done a show yet, and v0.5.0's new guards (system sounds, muting other apps, background work, interruptions, remote sessions) have only been checked on the bench. One correction: up to v0.5.0 the Mission Control guard didn't actually stop Mission Control on macOS 26, because the Dock ignores the setting it wrote. The fix is on main and not released yet. All the details are in the user guide.
v0.5.0 — prebuilt for macOS. Pick your platform:
macOS — Universal (Apple Silicon + Intel)
| Build | Download | Size |
|---|---|---|
| Universal (Apple Silicon + Intel) · .dmg disk image | showmode-0.5.0-macos-universal.dmg |
831 KB |
All builds, checksums and release notes: github.com/stoatworks-labs/showmode/releases.
macOS builds are signed and notarised by Apple, so they open normally — no Gatekeeper warning and no quarantine step.
| Guard | How |
|---|---|
| Display & system idle sleep | IOKit power assertions (die with the process) |
| Lid-close sleep (off by default) | pmset disablesleep 1 — admin prompt |
| Low Power Mode | pmset <source> powermode/lowpowermode 0, per power source — admin prompt, only if it is on |
| Fans (off by default, Apple silicon) | every fan fixed at its maximum (full speed) or minimum (quiet) through the SMC: mode key F0Md to 1 and target F0Tg to F0Mx or F0Mn, with the test flag Ftst set first where the SMC asks for it (M1–M4). Writing needs root, so a root helper holds them for the show — Show Mode's own executable, run from a copy of the bundle in a root-only directory once codesign has checked the copy against the running app's designated requirement. It hands the fans back to macOS at the end or as soon as Show Mode goes away. Quiet hands them back while macOS reports the Mac hot enough to slow down (thermalState serious) and takes them again after five cool minutes. Left alone if another app already has them — admin prompt |
| Screen saver | com.apple.screensaver idleTime 0 (current host) |
| Hot corners | all four wvous-* set to no-op, Dock restarted |
| Mission Control / App Exposé / gestures | the four Dock gesture keys, Dock restarted, and Mission Control's shortcuts off in WindowServer through SkyLight CGSSetSymbolicHotKeyEnabled, as ⌘Space is: ⌃↑ ⌃↓ and their ⇧ twins (32–35), F11 Show Desktop (36, 37) and the Mission Control key with each modifier (108–117). It also writes mcx-expose-disabled, which macOS 26's Dock ignores unless it's forced (next row) |
| Mission Control from mouse apps (off by default) | Logi Options+ and friends open Mission Control with CoreDockSendNotification (com.apple.expose.awake, com.apple.expose.front.awake), straight to the Dock, so no shortcut or event guard sees it. The Dock obeys mcx-expose-disabled only when CFPreferencesAppValueIsForced says so, so this writes it where a configuration profile would, /Library/Managed Preferences/<user>/com.apple.dock.plist, and restarts the Dock; read back from a fresh process, since one that has read the Dock's settings keeps its first answer. The file and any folder Show Mode made go at the end. Left alone where the Dock already has managed settings — admin prompt |
| Swipe between Spaces | Trackpad{Three,Four}FingerHorizSwipeGesture and the Magic Mouse's MouseTwoFingerHorizSwipeGesture, only where set to swipe between full-screen apps (2 → 0), then activateSettings -u so the trackpad driver rereads them; swipe between pages is left alone |
| Click wallpaper to show desktop | com.apple.WindowManager EnableStandardClickToShowDesktop |
| Desktop wallpaper | black on every screen (and any plugged in mid-show); the WallpaperAgent store is copied and put back, so dynamic/aerial wallpapers and every Space return exactly |
| Notifications | Do Not Disturb via two generated Shortcuts (see below) |
| System sounds | alert volume and "Play user interface sound effects" to 0 through AudioServices (ssvl, uion), the calls System Settings' Sound pane makes, and com.apple.sound.beep.feedback to 0 (an integer: loginwindow plays the pop and reads it as one); only where on, restored after. Output volume, mute and app audio are untouched |
| Other apps' sound (off by default, macOS 26+) | one private global Core Audio process tap (muteBehavior = .muted) mutes every app except those ticked under Allowed to Play, excluded by bundle ID (CATapDescription.bundleIDs) so one opened mid-show is simply heard; their helpers (com.google.Chrome.helper) count. Nothing reads the tap: no recording permission, no privacy dot. Measured by recording a loopback output: the mute takes hold of each sound as it starts, and a sound already playing when the show starts carries on until it stops, so the start-of-show note names those apps. It dies with Show Mode, so a crash brings sound back rather than silencing the show |
| Night Shift | CoreBrightness CBBlueLightClient — disabled and its schedule cleared |
| True Tone | CoreBrightness CBTrueToneClient |
| Auto light/dark appearance | SkyLight SLSSetAppearanceThemeSwitchesAutomatically(false) pins the showing appearance, the same call System Settings makes (the preference key alone changes nothing live); restored after |
| Colour-shift apps | quits f.lux, Shifty, Lunar; relaunches them after |
| Cursor fence | keeps the cursor off the screens you tick |
| Display arrangement | keeps the chosen (or starting) main display main, and splits any screen that starts mirroring mid-show back to extended |
| Privacy dots | SkyLight SLSSetSuppressPrivacyIndicatorOnExternalDisplays(true), the Privacy Indicators switch; only once the Recovery-only system-override suppress-sw-camera-indication-on-external-displays=on is set, and only on full-screen external displays (macOS rule). Restored after |
| Stage Manager | com.apple.WindowManager GloballyEnabled off, WindowManager restarted |
| ⌘Space | Spotlight's shortcuts (64 ⌘Space, 65 ⌥⌘Space) off in WindowServer through SkyLight CGSSetSymbolicHotKeyEnabled, which is not saved, so a restart mid-show brings them back anyway |
| Crash reports | com.apple.CrashReporter UseUNC: "quit unexpectedly" goes to Notification Center, where Do Not Disturb holds it, instead of a window. The report is still written |
| AirPlay Receiver | -currentHost com.apple.controlcenter AirplayReceiverEnabled off, which Control Center applies at once (macOS 26 spells it correctly; the older misspelling AirplayRecieverEnabled is written too). Frees TCP 5000/7000 and stops another device taking over the screen |
| Keyboard Setup Assistant | quit whenever it opens mid-show (a clicker or keypad that presents as a keyboard). Nothing to restore |
| Photo & media analysis | photoanalysisd and mediaanalysisd paused (SIGSTOP) by a sweeper, resumed (SIGCONT) at the end or as soon as Show Mode goes away. See Background work |
| App update checks | SUEnableAutomaticChecks off in each running Sparkle app's own defaults (Sparkle 2 watches the key while it runs); Microsoft AutoUpdate HowToCheck set to Manual unless the organisation manages it. Restored after |
| Syncthing | every folder that is syncing paused through Syncthing's local REST API (PATCH /rest/config/folders/<id>, key from its config.xml); only those are resumed |
| Sync apps | quits Resilio Sync, Synology Drive, MEGA, Sync.com and Box Drive, and opens them again after. Several sync through File Provider, which may carry on after the app quits |
| Time Machine (off by default) | tmutil stopbackup and tmutil disable — admin prompt, only if automatic backups are on. Read back after: without Full Disk Access tmutil reports success and changes nothing |
| Spotlight indexing (off by default) | Spotlight's importers (mdworker_shared, mdworker) paused by a root sweeper started from the admin prompt; mds and mds_stores keep running and answering searches |
| Automatic updates (off by default) | AutomaticDownload and AutomaticallyInstallMacOSUpdates (com.apple.SoftwareUpdate) and the App Store's AutoUpdate (com.apple.commerce) off — admin prompt; left alone on a managed Mac. Security responses and XProtect data are not touched |
| Remote sessions | every 5 s: inbound connections on 5900, 3283, 4000 and 7070 and TeamViewer's session process name the session in the menu and the log; the black wallpaper is put back if anything changed it |
| AWDL (expert, off by default) | ifconfig awdl0 down, held down by the root sweeper (macOS raises it again on its own). Costs AirDrop, peer-to-peer AirPlay, Sidecar and Universal Control |
| Look in use (experimental, off) | IOPMAssertionDeclareUserActivity every four minutes, so the untouched Mac is not taken for idle |
| Game Mode (experimental, off) | Xcode's gamepolicyctl game-mode set on, and the previous policy put back. Needs Xcode itself |
Tick the show screens under Keep cursor off. With Accessibility granted, an event tap rewrites any mouse move that would land on one so it ends up at the nearest point on a screen you're allowed, and the cursor never gets in. Without Accessibility, a 120 Hz poll warps it back, and the cursor is hidden while it's near a blocked screen so nobody sees it cross. The menu won't let you block the last unblocked screen (so a single-display Mac can't be fenced at all), and it asks before you block the main display, the one with the menu bar and Dock. If every screen somehow still ends up blocked, or the only allowed one gets unplugged, the fence stands down rather than trap the cursor somewhere you can't reach it.
Screens are remembered by vendor, model and serial, so your choice survives replugging and reboots.
The main display is made main by moving it to the origin of the global display space
(CGConfigureDisplayOrigin, every display shifted by the same amount, so the arrangement is
kept). A reconfiguration callback, debounced by a second, re-applies it and splits new mirrors
(CGConfigureDisplayMirrorOfDisplay(…, kCGNullDirectDisplay)); displays already mirrored at
start are left alone. If it has to put things right four times in twenty seconds it gives
up, on the basis that something else clearly wants the displays more than it does. The
previous main display is journalled and restored. Activity goes to ~/Library/Logs/ShowMode.log.
No app can hide the microphone, camera and screen-recording dots, so Show Mode tells you
about them instead.
WindowServer draws each dot as a window named StatusIndicator (readable without Screen
Recording access), which gives the screens showing one; CoreAudio process objects
(kAudioProcessPropertyIsRunningInput, macOS 14.2+) name the app on the microphone, and
CoreMediaIO says whether a camera is running. If neither, it is screen recording. The Recovery
override is read with /usr/bin/system-override <key>, which needs no root outside Recovery.
See the user guide for the one-time setup.
A show Mac left alone for hours looks idle, and idle is exactly when macOS and every other
app decide it's time for a spot of housekeeping. Processes that can only be paused, never
switched off, go to a
sweeper: a small shell loop that sends SIGSTOP to every process with one of a few exact names
every two seconds (so copies launchd starts mid-show are caught), and SIGCONT to them all when the
show ends. It learns that Show Mode has gone — crash and kill -9 included — from its end of a
pipe closing, never from a pid, and it gives up after three days regardless. The user-level
sweeper (media analysis) is Show Mode's child. Spotlight's _spotlight workers and AWDL need
root, so that sweeper starts from the show's one admin prompt, listens on a FIFO Show Mode holds
open, and has its script passed inline rather than from a file anyone could rewrite. At the end
Show Mode reads back what it paused and asks root to resume anything still paused.
What I leave alone on purpose: mds and mds_stores (stopping them hangs every search),
trustd, mobileassetd, softwareupdated, XProtect and the iCloud daemons, real-time
protection in any antivirus, launchctl on Apple services (SIP refuses it, or it does not stick),
and Apple Intelligence (turning it off can delete its models and download them again).
Some things no app can safely switch off, so Pre-show Checks lists them, each with the one thing you need to do: a macOS update waiting (someone choosing Install Tonight restarts the Mac overnight, which is a lovely surprise at call time), updates or Microsoft AutoUpdate managed by an organisation, Dropbox, Google Drive and OneDrive running (they can only be paused from their own menus; Dropbox keeps syncing after it quits), backup apps with schedules (Arq, Carbon Copy Cloner, Backblaze, ChronoSync), security software that opens its own windows or scans on a schedule (Intego, Sophos, Trend Micro, Norton, LuLu, BlockBlock, Defender, and IT-managed EDR, which is never touched), an active remote session, a display blacked out by a remote-access privacy mode, the Mac running hot, running on battery, and a network on Wi-Fi. The ones that can change mid-show stay at the top of the menu while it runs.
macOS doesn't let apps switch Focus, so Show Mode cheats. Setup → Install Do Not Disturb
shortcuts makes and signs two Shortcuts, "Show Mode Focus On/Off" (one Set Focus action
each), and Shortcuts asks you to add them once. After that Show Mode runs them with
shortcuts run.
Every change goes in a journal (~/Library/Application Support/ShowMode/journal.plist)
before it's made, along with the value it replaced, and restoring only undoes what Show Mode
changed. Ending show mode, quitting, SIGTERM/SIGINT/SIGHUP and relaunching after a crash all
restore.
Everything that needs root shares one password prompt at the start and one at the end, and each command runs whatever happened to the one before it. Cancelling the prompt at the start changes nothing. A command that fails keeps its journal entry, so the end writes the original back. At the end, anything whose command fails or whose prompt gets cancelled stays in the journal, the menu offers Finish Restoring, and the next launch has another go. Syncthing folders that couldn't be resumed (because Syncthing wasn't running yet at login) get retried the same way.
open showmode://on · off · toggle · fence-on · fence-off · wallpaper-black ·
wallpaper-restore — e.g. from Companion or a
show-control script. ShowMode --status prints what it can see without changing anything.
scripts/build-app.shThat builds a universal dist/Show Mode.app, Developer ID-signed if that identity is in the
keychain (a stable signature means the Accessibility grant survives rebuilds).
This project is built on other people's work — see ATTRIBUTIONS.md.