DoubleMouse

Ever wondered how to be faster on your Mac? What if, instead of one little arrow, you had two?

Meet DoubleMouse: a macOS menu bar app that lets you control your computer with two mice. One mouse keeps the normal macOS cursor; the second mouse gets its own blue pointer and can click independently.

It is also useful in teaching and support settings, where a teacher and a student can each have their own cursor on the same Mac. Less "move over, let me show you" and more "look, we both have arrows now."

Features

• Use a second physical mouse as an independent blue pointer.
• Keep the normal macOS cursor and the blue pointer independent in everyday use.
• Click with the blue pointer.
• Choose which physical device is the system mouse and which one drives the blue pointer.
• Lives quietly in the macOS menu bar.
• Open source Swift/AppKit implementation.

Behavior

macOS exposes one real system cursor. DoubleMouse works around that by drawing a virtual blue pointer for the secondary device, then briefly using the real cursor as an internal click executor. For blue-pointer clicks, it suppresses the secondary mouse's physical click and emits a synthetic click at the blue pointer instead.

This is not a kernel driver and not a native multi-cursor implementation. It does not promise true simultaneous pointer movement. It is a practical user-space approach for fast alternating control, teaching, demonstrations, and support sessions.

Current Limitations

• The blue pointer supports clicks, but not drag-and-drop yet.
• True simultaneous movement of both pointers is not supported.
• Some custom apps, games, canvases, or graphics tools may not respond to accessibility/synthetic clicks exactly like standard macOS controls.

Technical Notes

• Input is read per device with IOHIDManager.
• The blue pointer is drawn in a transparent always-on-top AppKit overlay.
• AppKit and CoreGraphics use different coordinate systems; click execution converts AppKit points to Quartz points before warping or posting events.
• Physical secondary clicks are suppressed with a short CGEventTap window.
• Synthetic DoubleMouse clicks are marked so the suppressor does not block its own events.

Usability Notes

• Quit any old DoubleMouse instance before testing a new build.
• If the wrong device controls the blue pointer, use Set Blue Pointer From Next Movement.
• If the blue pointer moves vertically in the wrong direction, toggle Invert Blue Pointer Y Axis.
• True simultaneous two-pointer movement is a future research area and likely requires a lower-level event-remapping approach.

Requirements

• macOS 13 or later.
• Xcode or Xcode Command Line Tools.
• Accessibility permission for blue-pointer clicks.

Run From Source

swift run DoubleMouse

While running from Terminal with swift run, macOS grants Accessibility permission to Terminal. A packaged app will request permission as DoubleMouse.

Try it with two pointing devices

1. Run swift run DoubleMouse.
2. Look for DoubleMouse in the macOS menu bar.
3. Choose the normal device under System Mouse.
4. Choose the device that should drive the blue overlay under Blue Pointer Mouse.
5. If needed, use Set Blue Pointer From Next Movement and then move the secondary mouse.
6. Move both devices to confirm the system cursor and blue pointer remain independent during normal alternating use.

The built-in MacBook trackpad may appear as a touchpad device on some Macs and macOS versions. If it does not appear, use the two external mouse setup first; trackpad support will need model-specific testing.

Project Status

DoubleMouse is an early working prototype. It is usable enough to demonstrate the idea, but still needs packaging, preference persistence, broader device testing, and UI polish.

Roadmap

• Package as a signed .app.
• Persist selected devices and pointer preferences.
• Improve the blue cursor artwork.
• Test more devices, including MacBook trackpad plus external mouse.
• Add releases with downloadable builds.
• Research true simultaneous movement through lower-level event remapping.
• Add drag-and-drop support for the blue pointer.

Contributing

Issues and pull requests are welcome. Please include your macOS version, device models, and whether you are testing with USB, Bluetooth, or built-in pointing devices.

License

MIT. See LICENSE.

This is an early prototype. The core movement separation is implemented with observed cursor cancellation, which is more stable than event suppression or cursor hiding on current macOS.