RFR: 8171898: [WebView] ScrollBarWidget thickness calculation is not correct

[Kevin Rushforth]

On Wed, 29 Apr 2020 11:03:22 GMT, Arun Joseph <ajoseph at openjdk.org> wrote:

>> While this might be the right fix, I don't think the evaluation is right. In particular, this doesn't look related to
>> [JDK-8157900](https://bugs.openjdk.java.net/browse/JDK-8157900). That refactoring fix was behavior neutral in terms of
>> the object graph -- it uses an accessor pattern rather than the removed public `impl_` methods for encapsulation, but
>> intentionally didn't change anything related to which instance of which objects are used. That fix was not backported
>> to 8u and yet this bug is listed as affecting 8u.  So, what I'd like to see in the evaluation is a description of the
>> root cause, and a brief explanation of the fix.  Can you also provide a test case that fails without the fix and passes
>> with the fix? I don't see one in JBS that you can leverage, so you may need to create one.
>
> This PR aims at modifying initializeThickness() to not use testSBRef and so, doesn't change the behavior of
> ScrollBarWidget. As it's not a bug, test case can't be created.

If it is not a bug, then why should we fix it?

-------------

PR: https://git.openjdk.java.net/jfx/pull/197