How is the problem manifesting itself??

Note: preferences related to the on-screen keyboard, if that is appearing unbidden, can be found in about:config by filtering on osk in the search box above the list.

There's no real problem. I just wanted to disable all touchscreen properties to test some other issues.  :-)

If in Windows Settings you have the on-screen keyboard turned off, you never have to worry about it appearing. As for fingerprints: I have a touchscreen (love it   ! ) and not ever do I see fingerprints   ....... You don't have to touch your touchscreen, though.

I'm not talking about the onscreen keyboard. I just don't want Firefox to respond if I touch the screen. Is this possible? I've done it with Chrome.

Thanks.

I don't have a touchscreen device to experiment with...

Is it possible that Windows 10 is sending "mouse" events to Firefox when you touch the screen, so that Firefox doesn't realize it's a touch event?

Or maybe dom.w3c_touch_events.enabled = 0 just doesn't work the way it used to.

What I do with my finger (on my touchscreen, that is) is no different than what I'd do with a mouse , or, in my case: with my touchpad. You have to be careful where to put your pointer; the same goes for where you put your finger.
I mainly use my touchscreen for scrolling:   so much faster than the scrollbar.