XPStyle keeps around a map that can include references to components. This is bad in that as XPStyle never goes away, the components can never be gc'd. Here's the reference list:

--> class com.sun.java.swing.plaf.windows.XPStyle (84 bytes) (static field xp:)
--> com.sun.java.swing.plaf.windows.XPStyle@0x19332e00 (17 bytes) (field borderMap:)
--> java.util.HashMap@0x19336860 (40 bytes) (field table:)
--> [Ljava.util.HashMap$Entry;@0x193bd538 (72 bytes) (Element 10 of [Ljava.util.HashMap$Entry;@0x193bd538:)
--> java.util.HashMap$Entry@0x194cbdc8 (24 bytes) (field key:)
--> com.sun.java.swing.plaf.windows.XPStyle$Skin@0x194d0020 (28 bytes) (field component:)
--> javax.swing.JToolBar@0x18ed27c8 (330 bytes) (field parent:)
--> javax.swing.JPanel@0x18ed25a8 (320 bytes) (field parent:)