How to add Tree inside JComboBox

[Mahesh Kedari]

Hi all,
Below is the requirement for which i need to add Tree inside JComboBox.
Im designing an inventory management application. While creating new product, I need to display a category and its sub category inside JComboBox. when user clicks on JComboBox, only parent categories should be displayed and when he clicks on + sign, child categories of selected category should be displayed.
The structure i m currently using is,
Add number of spaces before node name depending on the level of that node.
Like 3 spaces if its level is 3. etc.
I need to make this more user friendly adding JTree to JComboBox.

[Maneesh Godbole]

A simple google would have give you http://www.jroller.com/santhosh/entry/tree_inside_jcombobox