cascading richcombo

we want to implement a cascading dropdown by two richcombo in the same plagin.

 Someone have an idea how to implement this requirement.

We try to reset the list of second combo in the onclick event of the first combo and

loading the list by the "add" method and the javascript break in the "unmark" method.

the window.dropdown is the instance of the second combo which we save in the init 

event

window.dropdown = this;

This is the code

if (templateid != '') {

                                window.dropdown._.items = {};

                                var filteredBookmarks = window.bookmarks.filter(isInCurrentArray);

                                $.each(filteredBookmarks, function (index, value) {

                                    window.dropdown.add(value.TagName + "," + value.Description, 

value.Description);//init combo//self.add

                                });

                            }

Thanks