Adventures of a Flex developer

 package indecentmonkey.controls  
 {  
   import flash.events.Event;  
   import mx.controls.TextInput;  
   import mx.styles.CSSStyleDeclaration;  
   import mx.styles.StyleManager;  
   /**  
    * Colour of the outline of changed text  
    *   
    * @default 0x03ce02  
    */  
   [Style(name="itemConfigChanged", type="uint", format="Color", inherit="no")]  
   /**  
    * Colour of the outline of unchanged text  
    *   
    * @default 0xb7babc  
    */  
   [Style(name="itemConfigDefault", type="uint", format="Color", inherit="no")]   
   public class TextInputColour extends TextInput  
   {  
     public function TextInputColour() {  
       addEventListener(Event.CHANGE,handleColour);  
     }  
     /**  
      * @private  
      *   
      * We initialize the default styles for outline and fill styles by calling  
      * initStyles() when the component is instantiated.  
      */  
     private static var stylesInitialised:Boolean = initStyles();  
     /**  
      * @private  
      *   
      * The default styes are defined here.  
      */  
     private static function initStyles():Boolean {  
       var sd:CSSStyleDeclaration = StyleManager.getStyleDeclaration("TextInputColour");  
       if (!sd) {  
         sd = new CSSStyleDeclaration();  
         StyleManager.setStyleDeclaration("TextInputColour", sd, false);  
       }  
       sd.defaultFactory = function():void {  
         this.itemConfigChanged = 0x03ce02;  
         this.itemConfigDefault = 0xb7babc;  
       }  
       return true;  
     }  
     /**   
      * string to hold set text  
      */   
     private var _setText:String = "";  
     /**  
      * Handles initialization of this component.  
     */  
     override public function initialize():void {  
       super.initialize();  
     }  
     override public function set text(value:String):void {  
       super.text = value;  
       _setText = value;  
       handleColour(new Event(Event.CHANGE));  
     }  
     private function handleColour(e:Event):void {  
       if ( _setText == text ) {  
         setStyle("borderColor",getStyle("itemConfigDefault"));  
       }  
       else {  
         setStyle("borderColor",getStyle("itemConfigChanged"));  
       }        
     }  
   }  
 }