WebListbox - scrolling and focusring issues

When I run my web project in RS 2012r2.1, the WebListbox appears and behaves just fine: I can use my mouse’s scrollwheel to scroll up & down, and when I click into the listbox, it’s fine, too.

But when run from Xojo 2019r1, several ugly/bad things happen:

  1. Scrolling with the mouse wheel does not work any more. – How could this get broken with no one noticing?
  2. Clicking into the listbox draws a Focus Ring around the listbox. Why? How do I turn that off?

More issues with the scrollbar in the listbox:

  • Clicking into the scrollbar’s free area, i.e. outside of its handle bar, does scroll it to that position instead of paging up / down one page. That’s irregular - “normal” tables don’t do that, they behave as any other app on my Mac where I test this.
  • Clicking into the scrollbar’s top / bottom arrow buttons scrolls immediately to the top or bottom. That’s wrong behavior, too. It should scroll one line up/down.

Can someone comment on these issues? The is Listbox really that broken or am I just doing something wrong, somehow?

The focusring thing is basically intended on the web to ease navigation with the keyboard, or for impaired users.

There was a thread a couple weeks ago about that very topic:

The scroll issues is not reproducible in a small fresh project, so I assume it’s my fault, somehow. Maybe my CSS is at fault, or some other JS code that’s coming from JLTreeView, or something else. But I think I should be able to fix that myself when I slowly strip down my non-working project.