I'm running Office 2007 and would like to how to test if a particular Excel
addin (.xla) is already open within the current application.
I have tried finding it as a workbook (see below) but .xla files are not
included in the workbooks collection.

Dim WB as Workbook, WA as Workbook
For Each WB in Application.Workbooks
If WB.Name = "MyAddin.xla" then
Set WA = WB
Exit For
End if
Next WB
If Not WA is Nothing then ...