RFR: 8236651: Simplify and update glass gtk backend

Fri Jun 12 14:10:33 UTC 2020

On Fri, 12 Jun 2020 13:49:23 GMT, Thiago Milczarek Sayao <tsayao at openjdk.org> wrote:

> I had used two compilation parameters to limit Gtk on 3.8 (so it would generate error if any symbol > 3.8 were used).
> But that does not seem to work on 18.04, so I removed it.

Good. I was going to ask you about that, so I'm happy to see it gone.

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