This is a button on a page, not adding to the message bar. See how to edit the message bar here. https://us.tobiidynavox.com/blogs/support-articles/how-to-edit-the-message-bar-in-td-snap
Select the edit icon. Top right corner.
Select a button
Select the Active Label option, to the right of the label field.
Within the list choose the Message window Undo state or Redo state
Select Done.
Note: The button will remain grey unless there is something in the message windows that needs to be undone.
This feature is available with the TD Snap version 1.18 and above
