RFR: 8236651: Simplify and update glass gtk backend

[Kevin Rushforth]

On Mon, 6 Jan 2020 14:25:18 GMT, Kevin Rushforth <kcr at openjdk.org> wrote:

>> ### Summary
>> * Simplify and update the Gtk glass backend, making Linux a first-class OpenJFX platform.
>> 
>> ### Goals
>> * Make Linux a first-class OpenJFX platform (see Motivation);
>> * Simplify the code and reduce it's size;
>> * Update to gtk3 (it was originally a port from gtk2);
>> * Remove unused code (such as applets and web start);
>> * Prepare the ground for a possible future Wayland support.
>> ### Testing
>> ./gradlew -PEXTRA_TEST_ARGS='-Djavafx.gtk.experimental=true' -PFULL_TEST=true -PUSE_ROBOT=true :systemTests:test
>
>> Please, mark it as WIP.
> 
> You can do this by editing the title and adding `WIP: ` as a prefix.

This sort of enhancement needs to be discussed on the openjfx-dev mailing list first. While the WIP PR might be used to illustrate what you have in mind to propose, it is premature to actually review the implementation without first discussing whether and it makes sense to do it, what the high-level goals are, etc.

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