Bug 390669 [Accessibility]Press 'Tab' doesn't focus on the next report item when adding relative period aggregation.
xtab/org.eclipse.birt.report.item.crosstab.ui/src/org/eclipse/birt/report/item/crosstab/internal/ui/dialogs/CrosstabBindingDialogHelper.java
binding.setReferenceDateType( DesignChoiceConstants.REFERENCE_DATE_TYPE_TODAY );
			}
			else if ( dateSelectionButton.getSelection( ) )
			{
				binding.setReferenceDateType( DesignChoiceConstants.REFERENCE_DATE_TYPE_FIXED_DATE );
				ExpressionButtonUtil.saveExpressionButtonControl( dateText,
						binding,
						ComputedColumn.REFERENCE_DATE_VALUE_MEMBER );
			}
			else if ( recentButton.getSelection( ) )
			{
				binding.setReferenceDateType( DesignChoiceConstants.REFERENCE_DATE_TYPE_ENDING_DATE_IN_DIMENSION );
			}
		}
		return binding;
	}
	public static Expression getExpressionByControl( Control control )
			throws SemanticException
	{
		ExpressionButton button = getExpressionButton( control );
		if ( button != null && button.getExpressionHelper( ) != null )
		{
			Expression expression = new Expression( button.getExpressionHelper( )
					.getExpression( ),
					button.getExpressionHelper( ).getExpressionType( ) );
			return expression;
		}
		return null;
	}
	public ComputedColumnHandle newBinding( ReportItemHandle bindingHolder,