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
dialog.setCanFinish( false );
						this.messageLine.setText( Messages.getFormattedString( "BindingDialogHelper.error.nameduplicate", 
								new Object[]{
									txtName.getText( )
								} ) );
						this.messageLine.setImage( PlatformUI.getWorkbench( )
								.getSharedImages( )
								.getImage( ISharedImages.IMG_OBJS_ERROR_TSK ) );
						return;
					}
				}
			}
			
			
			
			if ( isAggregate( ) )
			{
				IAggrFunction function = getFunctionByDisplayName( cmbFunction.getText( ) );
				IParameterDefn[] params = function.getParameterDefn( );
				if ( params.length > 0 )
				{
					for ( final IParameterDefn param : params )
					{
						if ( param.isDataField( ) )
						{
							Combo cmbDataField = (Combo) paramsMap.get( param.getName( ) );
							String expression = cmbDataField.getText( );
							DataRequestSession session = null;
							try
							{