[9] Review Request: JDK-8037776 [macosx] Swing app fails to exit after last window is disposed when security manager is enabled

[Petr Pchelko]

Hello, AWT Team.

Please review the fix for the following issue: 
https://bugs.openjdk.java.net/browse/JDK-8037776
The fix is available at: http://cr.openjdk.java.net/~pchelko/9/8037776/webrev/

We are using a special thread to animate the warning window icon, but we do not 
shutdown it when disposing the security warning.
The test is so complicated because jtreg is killing the process itself and doe 
not let me test the issue.

With best regards. Petr.