Open any test suite in JavaTest, then View -> Properties. Close the dialog and the test suite.

Still, the whole test suite is retained in the memory due to improper cleanup in the ToolDialog.
Here's the proof (from JHat tool):

--> sun.awt.windows.WDialogPeer@0x4a9e670 (157 bytes) (field target:)
--> javax.swing.JDialog@0x4a9c6f0 (426 bytes) (field windowListener:)
--> com.sun.javatest.tool.ToolDialog$2@0x4aabf38 (12 bytes) (field this$0:)
--> com.sun.javatest.exec.PropertiesBrowser@0x4a4c9a0 (100 bytes) (field testSuite:)
--> com.sun.tck.msa.javatest.MSATestSuite@0x152abda0 (115 bytes)

So, the JDialog is not properly disposed and it keeps the reference to the test suite via its listener.
Attached patch fixes the problem for me.