A focus test java/awt/Focus/6981400/Test3.java works with Alt+Tab combinations and on some systems, namely on Xvnc which I have on Sparc, it lefts Alt key pressed after a test failure.
Why it fails is another question but without Alt release the system becomes rather unpredictable.

This test should be excluded from a massive run on the systems where it fails -- and/or be fixed to behave.
 
RULE "java/awt/Focus/6981400/Test3.java" Exception java.lang.RuntimeException: Test failed: the button is not a focus owner