There seems a small regression with JDK 1.6 with build 100.
If the ComboBoxModel is changed in the method
popupMenuWillBecomeVisible(PopupMenuEvent) then the size of the popup menu
will not corrected with the new model. The size of the popup menu is equals
the previous ComboBoxModel. With Java 5 the popup size is correct. Attached
attached a simple test case TestComboBox.java.