Upgrade from 1.1.2 to 1.3.0 causes janky scrolling.

I added a demo of the behavior I see.

There was some weird behavior in 1.1.2 where very rarely, I’d see my items flicker when I scrolled… upgraded to 1.3.0 thinking maybe that could help and it didn’t. You’ll notice this issue in my video as well.

Here is the video of 1.3.0:

https://streamable.com/brjpsj

You’ll see the janky scrolling is obvious and erratic. This was not happening in 1.1.2 - my scrolling was smooth.

As for the flickers, I recommend looking closely at the bottom right message at around 29 seconds. Another example is the message on the bottom left between seconds 34-35.

There are more instances of the flickers, but I pick out two cases.

<Virtuoso
      data={messages}
      overscan={6}
      followOutput="smooth"
      initialTopMostItemIndex={messages.length - 1}
      itemContent={(index, message) => { ... }} />

This is my code. I omit the item piece because I think it is irrelevant. Also, I switched margins on my item to padding like you suggest, so that isn’t causing the janky scrolling.

[dilizarov]

Also, I hope I don’t jinx myself, but I must say… If we ignore this bug, then this is the first time I’ve incorporated virtualization in a project and have said to myself “wow that was so simple and the results are amazing” instead of cursing and trying to get everything right. So kudos to you.

I’ve said it before, but this really is a magical library. I hope my results remain the same when I cross-browser test and test on mobile too 😂.

[dilizarov]

@petyosi I can confirm that this release https://github.com/petyosi/react-virtuoso/releases/tag/v1.2.5 causes the issue.

Will look into it a bit more.