Bug 136074 Filter editor needs to support column binding
In the Fitler tab of property editor for table/chart, Expression only shows dataset column, rather than column binding. Since column binding is supported for filter of table/chart, this is supposed to show the column binding.
UI/org.eclipse.birt.report.designer.ui/src/org/eclipse/birt/report/designer/ui/views/attributes/providers/SortingModelProvider.java
* @param keys
	 *            Property keys
	 * @return String array contains display names
	 */
	public String[] getColumnNames( String[] keys )
	{
		assert keys != null;
		String[] columnNames = new String[keys.length];
		for ( int i = 0; i < keys.length; i++ )
		{
			IStructureDefn structure = DesignEngine.getMetaDataDictionary( )
					.getStructure( SortKey.SORT_STRUCT );
			columnNames[i] = structure.getMember( keys[i] ).getDisplayName( );
		}
		return columnNames;
	}
	/**
	 * Gets all elements of the given input.
	 * 
	 * @param input
	 *            The input object.
	 * @return Sorts array.
	 */
	public Object[] getElements( List input )
	{
		Object obj = input.get( 0 );
		if ( !( obj instanceof DesignElementHandle ) )
			return EMPTY;
		DesignElementHandle element = (DesignElementHandle) obj;
		PropertyHandle propertyHandle = element.getPropertyHandle( ListingHandle.SORT_PROP );