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
{
		if ( calculationParamsValueMap.containsKey( name ) )
		{
			txtParam.setText( calculationParamsValueMap.get( name ) );
			return;
		}
	}
	private void initCalculationDataFields( Combo cmbDataField, String name,
			List<Period_Type> list )
	{
		String[] strs = new String[list.size( )];
		for ( int i = 0; i < list.size( ); i++ )
		{
			strs[i] = list.get( i ).displayName( );
		}
		cmbDataField.setItems( strs );
		if ( calculationParamsValueMap.containsKey( name ) )
		{
			cmbDataField.setText( calculationParamsValueMap.get( name ) );
			return;
		}
		cmbDataField.select( 0 );
	}
	private ITimeFunction getTimeFunctionByIndex( int index )
	{
		if ( times == null )
		{
			return null;
		}
		if ( index < 0 || index >= times.size( ) )