A tip from Scott:
Windows – Unhide, from the menu, shows the Unhide dialog box for unhiding workbooks.
Application.Dialogs(xlDialogUnhide).Show gets the job done.
Where it gets tricky is unhiding worksheets. Via the menu, Format – Sheets – Unhide
In vba, the name of the dialog is not so intuitive.
Poorly named, for sure, but you’ve been warned. Thanks Scott.