Regression test fails: closed/javax/swing/ToolTipManager/6256140/bug6256140.java

JDK: 7 b22
Tested OSes:
- Solaris nevada b70: sometimes test fails, sometimes test passes
- Linux i686: sometimes test fails, sometimes test passes
- Windows XP: test passes

Stack trace:
java.lang.RuntimeException: Tooltip is not shown
at bug6256140.main(bug6256140.java:56)
at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:57)
at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
at java.lang.reflect.Method.invoke(Method.java:623)
at com.sun.javatest.regtest.MainWrapper$MainThread.run(MainWrapper.java:78)
at java.lang.Thread.run(Thread.java:659)

The test logs in the attachment.