How to hide ListBox base on property value of another ListBox

[jon_n_topazsys]

I have a Basic MSI project with a dialog with two ListBox controls.  I 
want to hide the second ListBox when a given selection is made in the 
first ListBox.  Looking through the reference guide I haven't been able 
to find how to set the Visible property of the 2nd ListBox during installer
execution.  Nor have I been able to determine how to trigger this hiding 
action based of the first ListBox selecting a given value.  Do I need to 
trigger a custom action based on the first ListBox's PROPERTY value?   
How do I do that and what command do I use to set 2nd ListBox invisible?
I can see that the ListBox has a Visible property but I don't see how to
set it programmatically.