Bug 136270 Group's data binding column can only be used by the group itself
If you add some data binding columns to a group, these columns can only be used by this group itself. It should has a way to make the child can use the parent group's data binding column.
UI/org.eclipse.birt.report.designer.core/src/org/eclipse/birt/report/designer/util/DEUtil.java
* @param handle
	 * @param targetUnit
	 * @return
	 */
	public static double convertToValue( DimensionHandle handle,
			String targetUnit )
	{
		double retValue = 0.0;
		if ( handle.isSet( ) )
		{
			retValue = DimensionUtil.convertTo( handle.getMeasure( ),
					handle.getUnits( ),
					targetUnit ).getMeasure( );
		}
		return retValue;
	}
	/**
	 * Checks if the value can be converted to a valid Integer.
	 * 
	 * @param val
	 * @return true if the value can be converted to a valid Integer, else
	 *         false.
	 */
	public static boolean isValidInteger( String val )
	{
		try
		{
			Integer.parseInt( val );
		}
		catch ( Exception e )