expanding HBox during state change

the code adds a two line text Area upon state change with the checkBox being clicked.  The textArea is added, but the HBox component within the list is not causing the list items to expand downward - providing more room for the incoming text area.  

Basically - I'm looking for the the HBox custom component to expand and therefore the list elements positions to slide up and down as needed.

Three files:  myItemRenderer is the HBox with the state changes
MedList is the panel with the list
ViewStates is the main application - it also has a Form that expands and contracts to accomodate the incoming FormItem (a text input box).  This has the basic activity that I'd like to get with the HBox.