Bug 146159 [Regression]Changing font operation doesn't work other than the first time
Description: The first time changing operation can work well. However, Change it again, it won't work. Steps: 1.Insert lable/text to layout or master page 2.Change the font from serif to cursive, it works well 3.Change the font again Result: The action doesn't work Additional infor: build number:200606080632
UI/org.eclipse.birt.report.designer.core/src/org/eclipse/birt/report/designer/util/DEUtil.java
* @return Returns the definition, or null if the element is not defined.
	 */
	public static IElementDefn getElementDefn( String elementName )
	{
		IElementDefn defn = DesignEngine.getMetaDataDictionary( ).getElement(
				elementName );
		if ( defn == null )
		{
			defn = DesignEngine.getMetaDataDictionary( ).getExtension(
					elementName );
		}
		return defn;
	}
	/**
	 * Get display label of report element
	 * 
	 * @param obj
	 */
	public static String getDisplayLabel( Object obj )
	{
		return getDisplayLabel( obj, true );
	}
	/**
	 * Get display label of report element
	 * 
	 * @param obj
	 */
	public static String getDisplayLabel( Object obj, boolean includeElementName )
	{
		if ( obj instanceof DesignElementHandle )