Has anyone implemented it?
Can anyone share your code or thoughts on the topic please?
My investigation shows that overlay scrollbars are partially possible through pure CSS using non-standard overflow: overlay property but it has about 75% support only. And MDN marks overflow: overlay as deprecated for some time already. There is a bug thread of 2018 in Chromium where developer says the property value will be removed, but it is still supported in Chrome 96 at least (2022).
So I’m thinking to try to use some existing overlay scrollbars JavaScript library, or to try to port simplescrollbars from CM5.
Content in CM6 is virtualized so I’m not sure how third party scrollbars libraries would go.