For educational purposes,I'm am trying to create a macro
to use in an add-in that will select all of the sheets in
a workbook via use of an array. This macro will work in
the current workbook but does not seem to work when
applied to other workbooks. Would anyone have advice on
how this macro could be modified so that it could be
placed in the add-in and works when applied to other
workbooks?

Sub TestSelect()
Dim Sht() As String
Dim Cnt As Long
ReDim Sht(1 To ThisWorkbook.Sheets.Count)
For Cnt = LBound(Sht) To UBound(Sht)
ThisWorkbook.Sheets.Select
Next Cnt
End Sub

Thanks for your help.