JavaFX 2.0 :: WebEngine SetAttribute Is Not Reflected In WebView

I have a WebView which displays a site. At a specific page I want to fill in some values into <input> elements. So i use such an event handler (browser is of WebView class)
       
        browser.addEventHandler(MouseEvent.MOUSE_CLICKED,
                                new EventHandler<MouseEvent>(){
          public void handle(MouseEvent e) {           
            Document doc = webEngine.getDocument();
            if (doc == null) {
              System.out.println("Doc is null");

[Code] ....
 
The handler sets the "value" but view doesn't reflect that, field is empty.