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 DesignElementHandle avaliable method's argument type name.
	 * 
	 * @param handle
	 *            DesignElementHandle.
	 * @param methodName
	 * @param argIdex
	 *            starts from 0.
	 * @return
	 */
	public static String getMethodArgumentType( DesignElementHandle handle,
			String methodName, int argIndex )
	{
		if ( handle instanceof DataSetHandle )
			return ReportDesignConstants.DATA_SET_ELEMENT; 
		if ( handle instanceof DataSourceHandle )
			return ReportDesignConstants.DATA_SOURCE_ELEMENT; 
		List methods = handle.getDefn( ).getLocalMethods( );
		for ( Iterator iter = methods.iterator( ); iter.hasNext( ); )
		{
			IMethodInfo method = ( (ElementPropertyDefn) iter.next( ) )
					.getMethodInfo( );
			if ( method.getName( ).equals( methodName ) )
			{
				Iterator argumentListIterator = method.argumentListIterator( );
				if ( argumentListIterator.hasNext( ) )
				{
					IArgumentInfoList argumentInfoList = (IArgumentInfoList) argumentListIterator
							.next( );
					int i = 0;