RFR: 8252236: TabPane: must keep header of selected tab visible [v2]

[Ambarish Rapte]

On Fri, 18 Sep 2020 10:30:05 GMT, Jeanette Winzenburg <fastegal at openjdk.org> wrote:

>> the issue is that the header of the selected tab is not always visible (or kept visible, see report for details)
>> 
>> - initially
>> - after changing side
>> - after resizing stage/tabPane
>> - after modifying the list of tabs
>> 
>> Fixed in TabPaneSkin to notify its TabHeaderArea (== collaborator that is responsible for layout the tabs) whenever its
>> scroll might need an update.
>> Added tests that fail before and pass after the fix.
>> 
>> Note that there still are issues while/after dragging, which are separated into
>> [JDK-8253352](https://bugs.openjdk.java.net/browse/JDK-8253352)
>
> Jeanette Winzenburg has updated the pull request incrementally with one additional commit since the last revision:
> 
>   widened scope of fix to address review comment

Looks good to me, left a minor comment.

modules/javafx.controls/src/main/java/javafx/scene/control/skin/TabPaneSkin.java line 855:

> 853:                         } else {
> 854:                         }
> 855:                         validateScrollOffset();

This seems to be an unintended change. If so please revert.

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PR: https://git.openjdk.java.net/jfx/pull/300