package {
    import flash.display.*;
    import flash.events.*;
    import flash.text.*;
  
    // Demonstrates how to handle focus events for a single
    // object. Creates a TextField that, once focused, cannot be unfocused 
    // until at least three characters have been entered.
    public class @ax-actionscript-events-ObjectFocusSensor extends Sprite {
      private var namefield:TextField;
      private var passfield:TextField;
  
      public function @ax-actionscript-events-ObjectFocusSensor () {
        // Create text fields
        namefield = new TextField();
        namefield.width      = 100;
        namefield.height     = 30;
        namefield.border     = true;
        namefield.background = true;
        namefield.type = TextFieldType.INPUT;
  
        passfield = new TextField();
        passfield.width      = 100;
        passfield.height     = 30;
        passfield.y          = 50;
        passfield.border     = true;
        passfield.background = true;
        passfield.type = TextFieldType.INPUT;
  
        // Add text fields to the display list
        addChild(namefield);
        addChild(passfield);
        
        // Register for focus change events
        namefield.addEventListener(FocusEvent.MOUSE_FOCUS_CHANGE,
                                   focusChangeListener);
        namefield.addEventListener(FocusEvent.KEY_FOCUS_CHANGE, 
                                   focusChangeListener);
      }
  
      // Handle all focus change events targeted at namefield
      private function focusChangeListener (e:FocusEvent):void {
        if (e.target == namefield && namefield.text.length < 3) {
          trace("Name entered is less than three characters long");
          e.preventDefault();
        }
      }
    }
  }