True if the workbook is running as an add-in. Read/write Boolean.
Assembly: Microsoft.Office.Interop.Excel (in Microsoft.Office.Interop.Excel.dll)
When you set this property to True, the workbook has the following characteristics:
You won’t be prompted to save the workbook if changes are made while the workbook is open.
The workbook window won’t be visible.
Any macros in the workbook won’t be visible in the Macro dialog box (displayed by pointing to Macro on the Tools menu and clicking Macros).
Macros in the workbook can still be run from the Macro dialog box even though they’re not visible. In addition, macro names don’t need to be qualified with the workbook name.
Holding down the SHIFT key when you open the workbook has no effect.