RFR: 8243547: Lanai - Netbeans IDE has BLACK background for the Toolbar and Statusbar

[Ajit Ghaisas]

Issue : https://bugs.openjdk.java.net/browse/JDK-8243547
Root Cause : Rendering with transparent color (RGBA 0000) was resulting in solid black color.
Fix : Made MTLLayer translucent to support transparent color rendering.

-------------

Commit messages:
 - 8243547_netbeans_black_toolbar_fix

Changes: https://git.openjdk.java.net/lanai/pull/84/files
 Webrev: https://webrevs.openjdk.java.net/lanai/84/webrev.00
  Issue: https://bugs.openjdk.java.net/browse/JDK-8243547
  Stats: 11 lines in 4 files changed: 5 ins; 4 del; 2 mod
  Patch: https://git.openjdk.java.net/lanai/pull/84.diff
  Fetch: git fetch https://git.openjdk.java.net/lanai pull/84/head:pull/84

PR: https://git.openjdk.java.net/lanai/pull/84