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.setTimeDimension( dimensionName );
			binding.setCalculationType( timeFunction.getName( ) );
			binding.setProperty( ComputedColumn.CALCULATION_ARGUMENTS_MEMBER,
					null );
			
			for ( Iterator iterator = calculationParamsMap.keySet( ).iterator( ); iterator.hasNext( ); )
			{
				CalculationArgument argument = StructureFactory.createCalculationArgument( );
				String arg = (String) iterator.next( );
				argument.setName( arg );
				String value = getControlValue( calculationParamsMap.get( arg ) );
				if ( value != null )
				{
					if ( ExpressionButtonUtil.getExpressionButton( calculationParamsMap.get( arg ) ) != null )
					{
						Expression expr = getExpressionByControl( calculationParamsMap.get( arg ) );
						argument.setValue( expr );
					}
					else
					{
						Expression expr = new Expression( value,
								ExpressionType.JAVASCRIPT );
						argument.setValue( expr );
					}
					binding.addCalculationArgument( argument );
				}
			}
			
			if ( todayButton.getSelection( ) )
			{