new Text(box, SWT.MULTI  | SWT.WRAP | SWT.BORDER );

text.addListener(SWT.Modify, new Listener() {
  public void handleEvent(Event event) {
     //compute new Text field size
    Point size = text.computeSize(text.getSize().x, SWT.DEFAULT);

    //compute the difference between new and old Text field height
    int diff = size.y - text.getSize().y;
					
    if( expandItem != null )
    {
       //add diff to ExpandItems' height
      expandItem.setHeight(expandItem.getHeight() + diff);
    }
					
     //'reset' the layout if you are using one
    box.getParent().layout();
  }
});