What this cannot do

Blocked at the OS level while the app is in front: Cmd/Alt+Tab, F1–F20, Mission Control and Spaces, Spotlight, Cmd/Ctrl+Q W M H N T R P S O F J L D U, devtools shortcuts, zoom, Alt+F4, and screen capture (Print Screen and its variants, Cmd+Shift+3/4/5/6). Released the moment the window loses focus.

Not blocked, on purpose:

• Force Quit. Cmd+Alt+Esc on macOS, Ctrl+Alt+Del on Windows, and Ctrl+Shift+Esc. Left alone so the machine can always be recovered. Do not add these.

Held a different way, because Windows will not hand it over:

• The Windows key. A bare Super accelerator is rejected by Electron outright, and Windows refuses Super+D, Super+E, Super+R, Super+L, Super+Tab, Super+Shift+S and the rest when asked for them. Only Super+V, Super+Plus and Super+- are handed over, and those are taken.

  So pressing it opens the Start menu over the kiosk, and asking for focus back does nothing: Windows refuses a foreground request from a background process, and Start is drawn above every application window regardless of always-on-top.

  What works is Escape. While the lockdown is on, a PowerShell helper watches for the Start menu, Search and the quick settings panel, presses Escape on whichever appeared and brings the window back to the front, measured at about a quarter of a second. Any other foreground window is left alone, so keys are never sent into a dialog. The helper starts with the lockdown and stops with the app; nothing is installed and nothing on the machine is changed.

  Run npm run start-probe to watch it happen, and npm run key-probe to re-measure which keys this OS hands over.

On Linux the desktop’s own shortcuts are borrowed, not blocked. Alt+Tab and the Super key belong to GNOME rather than to any application, and under Wayland, the default on current Ubuntu, an application cannot intercept keys at all: Electron’s global shortcuts are an X11 facility, and on Wayland they report success and catch nothing.

So on a GNOME session Sukhi Play switches those bindings off in GNOME’s own settings while it runs, and puts them back exactly as they were when it quits. 25 of them, including Alt+Tab, the Super key, workspace switching and the screenshot keys.

Every original value is written to disk before anything changes, so a crash cannot leave you without Alt+Tab: the next start finds the backup and restores from it. Set borrowDesktopShortcuts to false in settings.json if you would rather it left your desktop alone.

On a desktop other than GNOME, choose Xorg at the login screen (the gear on the password field) for the in-app layer to work at all. The app says which session it found:

[gnome] borrowed 25 desktop shortcuts, including Alt+Tab and the Super key
[gnome] originals saved to ..., restored when this app quits

Cannot be blocked by any application:

• Hardware media keys. On a Mac, F-keys report as brightness, volume or Launchpad unless “Use F1, F2 as standard function keys” is on. The key never arrives as F4, so nothing can catch it.
• Trackpad swipes between Spaces. Handled by the window manager, never delivered to applications. The window follows onto the new Space, so your child still lands on Sukhi Play.

For a guarantee rather than a very good default, use a separate user account for your child, or Windows Assigned Access (Settings → Accounts → Set up a kiosk). Both are per-account and leave your own login untouched.

This is not a substitute for supervision. It reduces what a small child can reach; it does not childproof a computer.