Can't find changeHandler for combobox

I’ve created a combobox and added it to the stage. I’ve seem many tutorials where it tells you to create a function which will be called when the combobox value is selected. You can set the name of this function on the combobox interface in the component inspector, the parameter is called “changehandler”.

However, in CS4 I can’t find where to set the changeHandler. Can anyone tell me? Does it has to be set programmatically, and not in the interface?