Hey, we were testing this today and ran into some issues. I'm not entirely sure if this is what we should be testing, but we went to https://reactspectrum.blob.core.windows.net/reactspectrum/2c45388fdb4783f47e3f0d47112f89c90aafdc19/storybook/index.html?path=/story/react-aria-components-listbox--virtualized-list-box-grid&providerSwitcher-express=false

We added a 30px border to the virtualizer div aria-label="virtualized listbox", then tried drag and drop. On main, the drop indicator shows up on the next line down when you drag. We thought that this was what the PR was addressing, however, we saw the same behaviour here as well.

Can you clarify what this PR is addressing. What was broken and what it's fixing, as well as how to test it. Possibly adding a story could help.

Thanks!!

@snowystinger I'm confused, this change is in DOMLayoutDelegate, so why test virtualized scenarios? Am i missing the connection somewhere?

Otherwise, to give you more context on this change, it circles back to the pending RFC, which unfortunately is taking way longer to write up than I expected. I won't go much further into detail here, since it will become clear once that's PR'd, but essentially I'm using this delegate to scroll a "random access" item target rect to its scroll snap alignment - when the border is included, it causes target offsets not to lign up with visual position.

PS: Also noticed lately that contentSize should be diffed from first and last item instead of simply taking scrollWidth, in case scroll container is larger than content.

Apologies, it was a lot of delegates to follow around.
This story works for testing https://reactspectrum.blob.core.windows.net/reactspectrum/2c45388fdb4783f47e3f0d47112f89c90aafdc19/storybook/index.html?path=/story/react-aria-components-listbox--async-list-box&providerSwitcher-express=false

Manually adding border: 100px solid red on our main branch currently "overshoots" if you are focused on the first item, then you press page down
In this branch, it goes to the same place regardless of the border