Maybe, but the results might be weird.
I’ve set up a small test component (react) to experiment with a custom scrollbar, it can definitely be built…
If anyone wants to use the code, i’ll attach it here, but I won’t keep on working on it. There’s a lot of things that need to be handled (horizontal scrollbar, hide scrollbars when content fits, clicking on the track, …) and the code probably has some flaws (had to use setTimeout to get the actual height of the children elements).
The better choice would probably be to use an existing library and adjust it to fit to UXP if necessary.
Scroller.zip (1.3 KB)