import ThreadDataManager from './threadDataManager';

InboxSDK.load(...).then(sdk => {
  
  sdk.registerToolbarButtonForList({
    title: 'foo',
    ...
    onClick: (event) => {
      event.selectedThreadRowViews.forEach(threadRowView => {
        threadDataManager.setThreadData(threadRowView.getThreadID(), /* whatever data you want */);
      });
    }
  })
  
});