RFR: 8236651: Simplify and update glass gtk backend

Wed Jan 27 16:22:45 UTC 2021

On Mon, 25 Jan 2021 23:49:38 GMT, Kevin Rushforth <kcr at openjdk.org> wrote:

>> I would prefer this approach:
>> https://github.com/openjdk/jfx/pull/367
>
> Given the alternate approach that you propose to pursue (which I agree is a better option), this PR should either be closed or moved to Draft.

Closing it in favor of #367

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PR: https://git.openjdk.java.net/jfx/pull/77