macos - handle scaling

[softwaresinc]

On macos, the scaling gesture uses 2 fingers without pressing on the pad.
The current code effectively requires a finger press in order to start tracking finger motion.
This is fine for dragging but not scaling.

[taodo2291]

Due to the limitation of Flutter (Listener component), the scaling detects function will not work correctly with the touchpad device.
I cannot do anything about this. Hope you will find a solution soon.