> different platforms behave differently, and you can’t match it all

Why do I care about matching it all? Do we need a scrollbar with all kinds of bespoke per-platform functionality? If I have a scrollbar, that people can use to scroll on all platforms, and it fits the visual aesthetic of my application instead of looking like an absolute dogshit eyesore, is that not good enough? What percentage of the population would you reckon is shift+clicking their scrollbars on a routine enough basis to notice a web-app that doesn't meet their expectations? 1%? 0.1%? 0.0001%? And in this fail case, when they shift+click the scrollbar and it doesn't behave as they expected, how much harm is really being caused? Will it ruin their day or will they maybe just go 'tch' and then use the scrollbar normally to achieve their scrolling needs like everyone else?

Apparently I have angered the scrollbar shift+clicking hordes. There might be dozens of you!