user populate combobox

Can someone guide me with creating a user-editable combobox using flash mx 2004?

I want the user's entries to populate the combobox if unique.

I'm psuedo-thinking something like this, but I'm a newbie and need direction...

function add();

yourItem = myComboBox.getSelectedItem();
trace("You selected the item " + yourItem );


for (i=0; i=array.length; i++)
if (array[i] != yourItem)

{
addItemAt[0, yourItem]

else
break;

}



change handler is???