I can use the following code on a button on the cover sheet, but how do I
modify it if I want to use it in a form? When I use it it seems to see right
through it and click on the form itself.

Sub ShowSheetList()

On Error Resume Next
If ActiveWorkbook.Sheets.Count <= 16 Then
Application.CommandBars("Workbook Tabs"). _
ShowPopup 500, 225
Else
Application.CommandBars("Workbook Tabs"). _
Controls("More Sheets...").Execute
End If
On Error GoTo 0

End Sub