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
return DEUtil.findPos( parent, slotID, element );
	}
	/**
	 * Finds the position of the child element in the parent element with the
	 * given slotID
	 * 
	 * @param parent
	 *            the parent element
	 * @param slotID
	 *            the slotID
	 * @param child
	 *            the child element
	 * @return the position of the child element
	 */
	public static int findPos( DesignElementHandle parent, int slotID,
			DesignElementHandle child )
	{
		assert slotID >= 0;
		SlotHandle slotHandle = parent.getSlot( slotID );
		return slotHandle.findPosn( child );
	}
	/**
	 * Gets the element name. The object is a long string that separated with
	 * the separator "."
	 * 
	 * @param obj
	 *            the object
	 * @return the name behind the last separator "."
	 */
	public static String getElementName( Object obj )