When you send the file to co-workers, then those that have the add-in installed will have exactly the same view as you. When they don`t have the add-in installed, then the file will work exactly as normal ie: no multi-row sheet tabs, no filtering by color or tag etc. FormulaDesk Navigator is essentially a viewer – it allows you to see and work with sheet tabs in new ways. Also, the views aren`t turned on by default – you need to select the view from the ribbon menu, and you can turn it off again at any time to return to the `normal` Excel view.