RFR: 8327401: Some jtreg tests fail on Wayland without any tracking bug [v3]

[Alexander Zvegintsev]

> These changes are intended to stabilize testing on Wayland in X11 compatibility mode.
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> <hr>
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> Many tests may fail if there is no `robot.delay()` call after `robot.waitForIdle()` (right after displaying a window).
> <hr>
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> Some tests do not release previously pressed mouse button/key, this leads to other test failures later, but it is not a problem for X11 session.
> I haven't checked this, but it looks like the XWayland server does not release the key/button emulated by XTEST when the client application disconnects, while the regular X11 server does.
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> <hr>
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> For some tests it is critical to call AWT code on EDT(it prevents NPE):
> java/awt/List/KeyEventsTest/KeyEventsTest.java
> java/awt/Paint/ListRepaint.java
> 
> <hr>
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> Some other explanations can be found inline in the comments for a specific test.
> <hr>
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> Testing is green on all platforms.

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

  spacing

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Changes:
  - all: https://git.openjdk.org/jdk/pull/19339/files
  - new: https://git.openjdk.org/jdk/pull/19339/files/86f18e22..dd6b766b

Webrevs:
 - full: https://webrevs.openjdk.org/?repo=jdk&pr=19339&range=02
 - incr: https://webrevs.openjdk.org/?repo=jdk&pr=19339&range=01-02

  Stats: 2 lines in 2 files changed: 0 ins; 0 del; 2 mod
  Patch: https://git.openjdk.org/jdk/pull/19339.diff
  Fetch: git fetch https://git.openjdk.org/jdk.git pull/19339/head:pull/19339

PR: https://git.openjdk.org/jdk/pull/19339