Custom class propertyes

1

i have a class like this:

package 
{
    import flash.display.Sprite;
    
    public class chatBoxArea extends Sprite
    {
        
        public function chatBoxArea() 
        {
            this.graphics.beginFill(0x8080FF);
            this.graphics.drawRoundRect  (100, 100, 100, 100, 10, 10);
            this.graphics.endFill();
            
        }
        
    }

}

and in main class when i create new instance with:

var t:chatBoxArea  = new chatBoxArea ();

and after that try to chenge x,y,width,height propertyes like :

t.x = 500; 
t.y = 500;
t.width = 500;
t.height = 500;

i got stetch rounded rectangel…my question is how can i create class that can be change dinamicaly witouth streching?

i have tryed overiding setter for x,y,width,height and then graphic.clear() and recreate graphics but same effect.