public void setErrorMessage(String msg)
{
Document doc = itsNatDoc.getDocument();
Element errorElem = doc.getElementById("errorId");
ItsNatDOMUtil.setTextContent(errorElem,msg);
ElementCSSInlineStyle errorCSS = (ElementCSSInlineStyle)errorElem;
CSSStyleDeclaration style = errorCSS.getStyle();
style.removeProperty("display"); // makes visible
}