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
{
	/**
	 * Property name for element labelContent.
	 */
	public static final String ELEMENT_LABELCONTENT_PROPERTY = "labelContent"; 
	private static HashMap propertiesMap = new HashMap( );
	private static ArrayList notSupportList = new ArrayList( );
	static
	{
		propertiesMap.put( LabelHandle.TEXT_PROP, ELEMENT_LABELCONTENT_PROPERTY );
		propertiesMap.put( TextItemHandle.CONTENT_PROP,