[Development] QInputEvent refactoring

[Shawn Rutledge]

> On 2020 May 26, at 17:27, Shawn Rutledge <shawn.rutledge at qt.io> wrote:
>  If it worked with a native swipe gesture instead, maybe it would only receive the gesture if you are swiping from the screen edge, and only on certain platforms.

But the swipe gesture can be something else on touchpads, come to think of it; so maybe that’s useful on desktops after all.