At the time of writing, 2nd Jan 2025, Firefox has a bug that prevents UPDD Commander from being able to detect its UI elements during a gesture.
This bug applies when the following conditions are met:
- The touch screen being used is not the main display for the system
- The touch screen is not a high DPI display
- The main display is a high DPI display / retina display
Since the above three conditions are likely to be the case when using a touch screen as an external monitor on a Mac, especially a iMac or MacBook, we can't currently suggest using Firefox in cases where you need to be able to customise gestures depending on which of its UI elements are being gestured over.
Safari, Chrome, or another Chrome-based browser are better tailored for gesture use.