<i18n dev> RFR: JDK-8303950: [macos]Translucent Windows Flicker on Repaint [v4]

[Jeremy]

> I'm confident about the new test case for this ticket, but the resolution is more invasive than I'd like. (It works, though.)
> 
> In short:
> This introduces a new RenderingHint (in SunHints) to bypass the call in Window to `gg2d.fillRect(0, 0, getWidth(), getHeight());`
> 
> I left more detailed notes here about the proposed resolution:
> https://github.com/openjdk/jdk/commit/1991fdac5dbf76ddaf73cc78a9f7c38370c9674c
> 
> I'm open to suggestions if anyone has a more elegant proposal to prevent the monitor from refreshing too soon?

Jeremy has updated the pull request incrementally with one additional commit since the last revision:

  8303950: adding unit test for legacy window behavior
  
  This test passes in the current JDK. The test criteria don't really reflect a rational expected behavior; they just reflect the current status quo.
  
  This currently fails in this JDK-8303950 branch (using the new proposed AWTPaintManager), which indicates we've changed behavior.
  
  In this case it's "window 4" that's failing. We used to get a mostly blue background, and now we're getting a background that's mostly red with a little blue. This isn't necessarily a bad thing; this failure is just documenting a change.

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Changes:
  - all: https://git.openjdk.org/jdk/pull/12993/files
  - new: https://git.openjdk.org/jdk/pull/12993/files/960fd176..bd81761a

Webrevs:
 - full: https://webrevs.openjdk.org/?repo=jdk&pr=12993&range=03
 - incr: https://webrevs.openjdk.org/?repo=jdk&pr=12993&range=02-03

  Stats: 131 lines in 1 file changed: 131 ins; 0 del; 0 mod
  Patch: https://git.openjdk.org/jdk/pull/12993.diff
  Fetch: git fetch https://git.openjdk.org/jdk.git pull/12993/head:pull/12993

PR: https://git.openjdk.org/jdk/pull/12993