Bug 450678

SUMMARY
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STEPS TO REPRODUCE
1. Open a text file long enough to scroll through.
2. Use MacOS's built-in two-finger scroll gesture using the touchpad.

EXPECTED RESULT
When natural scrolling is turned OFF – two fingers are slided down to scroll down, and vice versa.
When natural scrolling is turned ON – two fingers are slided up to scroll down, and vice versa.

In both cases, no jitter or lag should exist.

OBSERVED RESULTS
When natural scrolling is turned OFF – scrolling moves up and down repetitively until it settles. (see https://youtu.be/QvMhfuosyoo)
When natural scrolling is turned ON – same behaviour as above, but only present when scrolling at the top of the document. (see https://youtu.be/2Hr82n2sB-k)

None of these lead to a crash, but incredibly annoying when trying to do work.

SOFTWARE/OS VERSIONS
macOS: Darwin 21.3.0 x86_64
KDE Plasma Version: N/A
KDE Frameworks Version:  5.90.0
Qt Version: 5.15.2 (built against 5.15.2)