Should work for trackpads connected after starting the app

[filippo-orru]

Describe the bug
Currently, when MiddleDrag starts, it applies the three-finger gesture for all connected devices. When connecting a new trackpad (Magic Trackpad) while MiddleDrag is already running, thre-finger taps don't work on the new device.

To Reproduce
Steps to reproduce the behavior:

1. Connect Magic Trackpad
2. Start Middle Drag
   -> the three finger tap works as expected
3. Disconnect and reconnect Magic Trackpad
   -> the three finger tap does not work

Expected behavior
The app should also work when disconnecting or reconnecting devices.

Screenshots
N/A

Desktop (please complete the following information):

• OS: MacOS 26.3.1
• Middle Drag version v1.4.3

Additional context
I looked into fixing this myself, see my commit here: filippo-orru@0f15313

I modified DeviceManager.swift to regularly check for new devices. This does work but it logs "Registered 3 newly connected multitouch device(s)" every 2 seconds. Pointers returned by MTDeviceCreateList() change with every invocation, so I wasn't able to check if a callback was already registered for this device's pointer. Maybe you're able to figure it out, I don't know enough about MacOS private framework internals 🙂

While researching this, I also stumbled upon https://github.com/artginzburg/MiddleClick. It's written in Obj-c and only handles middle click (not drag) but that's all I need. It does support reconnecting devices, so maybe you can check it out and see how they query multi touch devices.
Another related repo (written in Swift, might be easier to digest): https://github.com/ris58h/Touch-Tab

[NullPointerDepressiveDisorder]

Thank you for such a detailed and well written issue! I will definetly see what I can do

[NullPointerDepressiveDisorder]

@filippo-orru Hey, I dont have a magic tracpad to test this patch on. Would you be up for testing the linked pr yourself? If not, no big deal, Ill just merge it as it doesn't affect other functionality.