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
session = DataRequestSession.newSession( new DataSessionContext( DataSessionContext.MODE_DIRECT_PRESENTATION ) );
								if ( session.getCubeQueryUtil( )
										.getReferencedMeasureName( expression ) != null
										&& function.getType( ) == IAggrFunction.RUNNING_AGGR )
								{
									dialog.setCanFinish( false );
									this.messageLine.setText( Messages.getFormattedString( "BindingDialogHelper.error.improperexpression", 
											new Object[]{
												function.getName( )
											} ) );
									this.messageLine.setImage( PlatformUI.getWorkbench( )
											.getSharedImages( )
											.getImage( ISharedImages.IMG_OBJS_ERROR_TSK ) );
									return;
								}
								dialog.setCanFinish( true );
							}
							catch ( Exception e )
							{
							}
							finally
							{
								if ( session != null )
								{
									session.shutdown( );
								}
							}
						}
					}
				}