Create a regression test for JDK-7184401

Create a regression test for
JDK-7184401: JDk7u6 Missing main menu bar in Netbeans after fix for 7162144
As indicated in the above bug's description, the issue got introduced due to a fix for JDK-7162144. The test below recreates a standalone test to mimic the failure reported in Netbeans in JDK-7184401 and verifies that it is working as expected after it got fixed.( Via JDK-7189350)

The Test attempts to reproduce specific behavior of NetBeans at the certain toolbar creation stage. Widgets are created on EDT; Another code posts some events to them on EDT; From another thread some code calls explicitly edt.interrupt().
Before this got fixed, events from a second code got lost.