[OpenJDK 2D-Dev] RFR: 8266079: Lanai: AlphaComposite shows differences on Metal compared to OpenGL [v4]

[Alexey Ushakov]

> Keep MTLLayer opacity in sync with window content view
> Keep layer translucent for translucent windows

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

  8266079: Lanai: AlphaComposite shows differences on Metal compared to OpenGL
  
  Removed unnecessary initialisation of opacity

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Changes:
  - all: https://git.openjdk.java.net/jdk/pull/4946/files
  - new: https://git.openjdk.java.net/jdk/pull/4946/files/f7a003af..02056138

Webrevs:
 - full: https://webrevs.openjdk.java.net/?repo=jdk&pr=4946&range=03
 - incr: https://webrevs.openjdk.java.net/?repo=jdk&pr=4946&range=02-03

  Stats: 1 line in 1 file changed: 0 ins; 1 del; 0 mod
  Patch: https://git.openjdk.java.net/jdk/pull/4946.diff
  Fetch: git fetch https://git.openjdk.java.net/jdk pull/4946/head:pull/4946

PR: https://git.openjdk.java.net/jdk/pull/4946