A JComboBox dropped down list does not become hidden even if the focus is shifted to some other component using the tab key. This occurs only for editable JComboBox. And this does not occur if the combobox is edited before pressing the tab key. This occurs on all platforms with tiger.

Steps to reproduce:
1. Run the attached testcase
2. Drop down the JComboBox. Press the arrow key to change the selection.
3. Type the tab key to change the focus to the next combobox. You can edit the combobox. Still the drop down list of the first combobox is visible.
4. You can press tab to change the focus to the Button, which is not visible now and press the tab key to generate action event.