[jdk21u-dev] RFR: 8346839: [TESTBUG] "java/awt/textfield/setechochartest4/setechochartest4.java" failed because the test frame disappears on clicking "Click Several Times" button

[Goetz Lindenmaier]

I backport this for parity with 21.0.10-oracle.

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Commit messages:
 - Backport 58270b757c0bdf82bf753fa304b829e3b64196e4

Changes: https://git.openjdk.org/jdk21u-dev/pull/2379/files
  Webrev: https://webrevs.openjdk.org/?repo=jdk21u-dev&pr=2379&range=00
  Issue: https://bugs.openjdk.org/browse/JDK-8346839
  Stats: 16 lines in 1 file changed: 1 ins; 4 del; 11 mod
  Patch: https://git.openjdk.org/jdk21u-dev/pull/2379.diff
  Fetch: git fetch https://git.openjdk.org/jdk21u-dev.git pull/2379/head:pull/2379

PR: https://git.openjdk.org/jdk21u-dev/pull/2379