[jdk11u-dev] RFR: 8172269: When checking the default behaviour for a scroll tab layout and checking the 'opaque' checkbox, the area behind tabs is not red.

[Goetz Lindenmaier]

I backport this to fix an error in the tabbed pane.

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Commit messages:
 - Backport eb91535be50d1c9882ec7a724dd247ece67a8266

Changes: https://git.openjdk.org/jdk11u-dev/pull/1453/files
 Webrev: https://webrevs.openjdk.org/?repo=jdk11u-dev&pr=1453&range=00
  Issue: https://bugs.openjdk.org/browse/JDK-8172269
  Stats: 146 lines in 2 files changed: 142 ins; 1 del; 3 mod
  Patch: https://git.openjdk.org/jdk11u-dev/pull/1453.diff
  Fetch: git fetch https://git.openjdk.org/jdk11u-dev pull/1453/head:pull/1453

PR: https://git.openjdk.org/jdk11u-dev/pull/1453