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
List bindingList = new ArrayList( );
		if ( handle instanceof ReportElementHandle )
		{
			Iterator iterator = getBindingColumnIterator( handle );
			while ( iterator.hasNext( ) )
			{
				bindingList.add( iterator.next( ) );
			}
			bindingList.addAll( 0,
					getAllColumnBindingList( handle.getContainer( ), true ) );
		}
		return bindingList;
	}
	/**
	 * Returns all visible column bindings in the holder scope for the given
	 * element
	 * 
	 * @param handle
	 *            the handle of the element
	 * @return the list of all visible column bindings.The list order is from
	 *         the top to the given element
	 */
	public static List getVisiableColumnBindingsList( DesignElementHandle handle )
	{
		return getVisiableColumnBindingsList( handle, true );
	}
	/**
	 * Returns all visible column bindings for the given element
	 * 
	 * @param handle