RFR: 8311185: VirtualFlow jump when cellcount changes

[Kevin Rushforth]

On Fri, 30 Jun 2023 17:43:56 GMT, Johan Vos <jvos at openjdk.org> wrote:

> When the cellcount changes, we need to make sure that the size of the current first visible cell is known.
> 
> This avoids index errors due to the current offset (between the top of the viewport and the current first visible cell) being potentially larger than the new estimated cellsize.
> 
> Added a test that fails before and succeeds after the patch. The test uses the same logic as the reproducer in the JBS issue.

The fix looks good to me, as does the test. I can confirm that the test program attached to the JBS issue now works, and that the new unit test fails without the fix and passes with the fix.

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Marked as reviewed by kcr (Lead).

PR Review: https://git.openjdk.org/jfx/pull/1164#pullrequestreview-1531437130