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Magic Mouse middle click, and why the App Store version can’t do it

WheelClick gives the Magic Mouse a middle click: rest three fingers on its surface and click. The version from this site does it. The App Store version doesn’t — not by choice, and not because it was left out.

The gestures

Four of them, each independent, each affecting only the mouse — trackpad settings are never touched.

• Click with three fingers. On by default. The mouse twin of the trackpad’s three-finger click.
• Click with one finger in the center. The strip between the left- and right-click zones.
• Click with two fingers. Off by default — resting index and middle finger while clicking is a common grip.
• Tap with three fingers. A light tap, no press.

fn+click works on a Magic Mouse in both versions. It answers the key held during the press, and a press carries no device — so it needs nothing from the mouse’s touch surface. If you’re on the App Store version and want a middle click on your mouse today, that is the one that works.

Why the App Store version can’t

A trackpad hands its fingers to any app through macOS itself. A Magic Mouse doesn’t. Its driver takes the contacts, turns them into a small vocabulary of finished gestures — scroll, swipe, that’s roughly it — and the raw fingers never reach a normal app at all. We checked every public route there is, each time with a trackpad running alongside as a control: touch data on gesture events, event taps at two levels, monitors, the responder chain, every numeric field on the raw event, HID input reports, HID element values. The trackpad answered on almost all of them. The mouse answered on none.

One door does open — a private Apple framework, undocumented and unsupported — and it opens only outside the App Sandbox. Inside it, the call to start reading simply fails, with nothing logged and no error to catch. So the version on this site keeps the app sandboxed and puts that one piece in a tiny separate program alongside it, which does nothing but count fingers and report the number. An App Store app may not contain a program like that, and Apple reviews every binary inside a bundle — so the App Store build ships without it, and says so rather than showing you switches that can’t work.

What it costs

Measured on a real Magic Mouse, across both processes, not estimated:

• Mouse switched off, or none attached — nothing. No extra draw at all, and the finger-counting program isn’t running: it starts when a mouse appears and exits when it leaves.
• Mouse on, hand off it — nothing measurable. Zero processor time, zero wake-ups.
• Hand actually on the mouse — 0.9 mW. Less than the menu bar clock, and only while you’re touching it.

Every gesture in WheelClick carries a measured energy figure in its own menu, on the same principle: a number that was read off the hardware, or no number at all. What those numbers mean, and the A–G scale they are placed on, is a page of its own — including why the Magic Mouse figure had to be taken with a real hand rather than a script.

Which version does what

• Trackpad gestures — both versions, identical.
• fn+click, on any mouse — both versions.
• Magic Mouse touch gestures — this site’s version only.

If you already bought on the App Store and this is what you came for, email support@wheelclick.app — we’ll sort it out.