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
*/
	public static Iterator getStyles( Comparator comparator )
	{
		List styles = SessionHandleAdapter.getInstance( )
				.getReportDesignHandle( )
				.getAllStyles( );
		Object[] stylesArray = styles.toArray( );
		if ( comparator != null )
		{
			Arrays.sort( stylesArray, comparator );
		}
		return Arrays.asList( stylesArray ).iterator( );
	}
	/**
	 * Checks if two strings have same value.
	 * 
	 * @param str1
	 * @param str2
	 * @return
	 */
	public static boolean isSameString( String str1, String str2 )
	{
		if ( str1 == null && str2 == null )
		{
			return true;
		}
		if ( str1 != null && str1.equals( str2 ) )
		{
			return true;
		}