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
ModuleHandle module = ( (ExtendedItemHandle) xtabHandle.getModelHandle( ) ).getModuleHandle( );
		List<IBinding> bindingList = new ArrayList<IBinding>( );
		if ( bindingItr != null )
		{
			Map cache = new HashMap( );
			List rowLevelNameList = new ArrayList( );
			List columnLevelNameList = new ArrayList( );
			DataRequestSession session = DataRequestSession.newSession( new DataSessionContext( DataSessionContext.MODE_DIRECT_PRESENTATION ) );
			try
			{
				IModelAdapter modelAdapter = session.getModelAdaptor( );
				while ( bindingItr.hasNext( ) )
				{
					ComputedColumnHandle column = (ComputedColumnHandle) bindingItr.next( );
					
					IBinding binding;
					try
					{
						binding = modelAdapter.adaptBinding( column,
								ExpressionLocation.CUBE );
					}
					catch ( Exception e )
					{
						continue;
					}
					if ( binding == null )
					{
						continue;
					}