Bug 214212 Problem occurs when set the masterpage margin with ems/exs/pixcel units.
model/org.eclipse.birt.report.model/src/org/eclipse/birt/report/model/metadata/DimensionPropertyType.java
* <li>An <code>Integer</code>,<code>Float</code>,
	 * <code>Double</code> or <code>BigDecimal</code>. Assume that the
	 * units are specified by the design default.</li>
	 * </ul>
	 * 
	 * @return object is of type <code>DimensionValue</code> or null.
	 */
	public Object validateValue( Module module, PropertyDefn defn, Object value )
			throws PropertyValueException
	{
		if ( value == null )
		{
			logger.log( Level.FINE, "The input value object is null." ); 
			return null;
		}
		if ( value instanceof String )
			return validateInputString( module, defn, (String) value );
		if ( value instanceof DimensionValue )
		{
			if ( !StringUtil.isBlank( ( (DimensionValue) value ).getUnits( ) ) )
			{
				logger
						.log(
								Level.FINE,
								"Validate the dimension value with defined unit " + value ); 
				return value;
			}
			logger.log( Level.FINE,
					"return dimension value with default unit " + value ); 
			return new DimensionValue(