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
for ( int i = 0; i < DATA_TYPE_CHOICES.length; i++ )
			{
				if ( DATA_TYPE_CHOICES[i].getDisplayName( )
						.equals( cmbType.getText( ) ) )
				{
					binding.setDataType( DATA_TYPE_CHOICES[i].getName( ) );
					break;
				}
			}
			binding.setAggregateFunction( getFunctionByDisplayName( cmbFunction.getText( ) ).getName( ) );
			ExpressionButtonUtil.saveExpressionButtonControl( txtFilter,
					binding,
					ComputedColumn.FILTER_MEMBER );
			binding.clearAggregateOnList( );
			
			{
				String aggStr = cmbAggOn.getText( );
				StringTokenizer token = new StringTokenizer( aggStr, "," ); 
				while ( token.hasMoreTokens( ) )
				{
					String agg = token.nextToken( );
					if ( !agg.equals( ALL ) )
						binding.addAggregateOn( agg );
				}
			}
			
			binding.setExpression( null );
			binding.clearArgumentList( );
			for ( Iterator iterator = paramsMap.keySet( ).iterator( ); iterator.hasNext( ); )
			{