Polish: va-virtual-scroller

[asvae]

• Disabled prop doesn't function according to docs.
  • Here's what it says in docs Applies disabled style and removes all user interaction effects..
  • Right now it just shows all items instead of visible items subset.
  • I suggest we check other references to make sure that current implementation is a good idea. I wouldn't assume disable disables virtual scroll, but rather makes whole element inactive (but that's just me).
• DifferentSizesAndMargins story is a bit too complex (even uses buttons for some reason). We can probably simplify it.
• track-by is not tested properly and story has no visual hints whether it works or not.