There’s also a problem with the inertia. Recently @SQUARESEQUENCE posted a workaround which addresses both issues:
The other issue is that swiping pages with GUI elements does not work as one would expect. If one begins a swipe movement over a button, one expects to swipe the viewport, not click the button. So one needs a considerable amount of custom code to get things to work properly and things get tricky when it comes to comboboxes, sliders, a viewport inside the viewport, etc.
I think an update of the Viewport which fixes these issues and adds a swiping mode which behaves as in iOS and Android would be a very reasonable feature request!