RFR: 8303680 Virtual Flow freezes after calling scrollTo and scrollPixels in succession

[Johan Vos]

On Tue, 7 Mar 2023 09:47:39 GMT, Florian Kirmaier <fkirmaier at openjdk.org> wrote:

>> modules/javafx.controls/src/main/java/javafx/scene/control/skin/VirtualFlow.java line 1718:
>> 
>>> 1716:         // Finally, update the scroll bars
>>> 1717:         updateScrollBarsAndCells(false);
>>> 1718:         lastPosition = getPosition();
>> 
>> This is not a formal review -- I'll let Andy and Johan do that -- but can you explain why this is the right fix? Presumably there was at least some reasoning behind updating `lastPosition`. Are there any side effects of not doing that?
>
> I've written more about the explanation below. Actually, it's a good question whether there is reasoning behind updating lastPosition. Wouldn't be surprised, if it is just an artifact of some bug-fixing attempt.

I'll review this. 
One of the challenges with the VirtualFlow class is that there are a number of parameters that contain some state, and the behavior depends very often on what parameters are modified in which method, and when (in which order).

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PR: https://git.openjdk.org/jfx/pull/1052