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
items[i] = times.get( i ).getDisplayName( );
			names[i] = times.get( i ).getName( );
		}
		calculationType.setItems( items );
		if ( getBinding( ) == null )
		{
			if ( cal != null && getItemIndex( items, cal ) >= 0 )
			{
				calculationType.select( getItemIndex( items, cal ) );
			}
			else
			{
				calculationType.select( 0 );
			}
			handleCalculationSelectEvent( );
		}
		else
		{
			if ( cal != null && getItemIndex( items, cal ) >= 0 )
			{
				calculationType.select( getItemIndex( items, cal ) );
			}
			else
			{
				ITimeFunction function = getTimeFunctionByDisplaName( getBinding( ).getCalculationType( ) );
				if ( function == null )
				{
					return;
				}
				String name = function.getName( );