I am implementing a comboBox consisting of normal comboBoxItems and those which will allow the modification of the list bound to the comboBox.

Eg: I need the following to go into the comboBox - option1, option2, option3, AddNewOption where, upon clicking on the AddNewOption, I want the comboBoxItem to expose a textBox where I enter the content, which will be dynamically added to the list bound to the comboBox.

How do I implement the highlighted portion?