RFR: JDK-8222323: ChildAlwaysOnTopTest.java fails with "RuntimeException: Failed to unset alwaysOnTop" [v4]

[Harshitha Onkar]

> This test case tests the functionality of `setAlwaysOnTop`. 
> Documentation on `setAlwaysOnTop`: [Link](https://docs.oracle.com/en/java/javase/17/docs/api/java.desktop/java/awt/Window.html#setAlwaysOnTop(boolean))
> 
> The following test case was seen to fail on windows and linux platforms. With the proposed fix, the test case works on all platforms.
> 
> The test case tests `alwaysOnTop` for the following three cases:
> 
> 1.	JDialog with no parent/owner
> 2.	JDialog with JFrame as owner
> 3.	JDialog with another JDialog as owner
> 
> Each of the three cases mentioned above is tested under 3 scenarios:
> ![Screen Shot 2022-05-02 at 2 02 30 PM](https://user-images.githubusercontent.com/95945681/166327299-0fb5ce14-478d-4dee-a03a-1009a8e17047.png)

Harshitha Onkar has updated the pull request incrementally with one additional commit since the last revision:

  added error msgs to StringBuffer

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

Changes:
  - all: https://git.openjdk.java.net/jdk/pull/8509/files
  - new: https://git.openjdk.java.net/jdk/pull/8509/files/e4b7740d..79120c79

Webrevs:
 - full: https://webrevs.openjdk.java.net/?repo=jdk&pr=8509&range=03
 - incr: https://webrevs.openjdk.java.net/?repo=jdk&pr=8509&range=02-03

  Stats: 17 lines in 1 file changed: 2 ins; 7 del; 8 mod
  Patch: https://git.openjdk.java.net/jdk/pull/8509.diff
  Fetch: git fetch https://git.openjdk.java.net/jdk pull/8509/head:pull/8509

PR: https://git.openjdk.java.net/jdk/pull/8509