var myKeyListener = new Object();
myKeyListener.onKeyUp = function() {
var myString = myTextfield.text;
var firstLetter = (myString.charAt(0)).toUpperCase();
var remainderLetters = (myString.substring(1)).toLowerCase();
var myNewString = firstLetter+remainderLetters;
myTextfield.text = myNewString;
};
Key.addListener(myKeyListener);

//construct the listener object
myListenerObject = new Object();
 
myListenerObject.onChanged = function(txt) {
//perform this when textfield value has changed
execute();
}
 
//call the TextField.addListener method to register the object
Textfield.addListener(myListenerObject);