User FAQs

If you have a question, please send it to us.

1) Can you describe Ribbon Customisation ?
Allows you to add (or replace) functionality to existing tabs, create new tabs, groups and commands.
This can be done using NotePad
If you have a Visual Studio Template this can also be done using the Ribbon (Visual Designer).

2) Are the Office PIAs (Primary Interop Assemblies) included with an Office 365 installation ?
No. These PIA files are included as part of Visual Studio but they are not included with Office 365, Office 2019 or Office 2016.
You should make sure the PIAs have the Embed Interop Type option set to True.

3) Is the VSTO Runtime included with an Office 365 installation ?
No. For Office 2013 and Office 2010 a 32-bit version of the runtime was installed automatically if .NET Framework 3.5 was already installed.
You should make sure the 2010 VSTO Runtime (v4) - 64 and 32 bit version is included as a prerequisite for your solution.

4) What is the Office namespace/reference used for ?
This namespace contains the core objects that are shared across all the different Office 2013 applications.
Office 2013 was the last version to have Primary Interop Assemblies.
This assembly is automatically added when you create a new VSTO add-in from the "Create a new Project" wizard dialog box.

Folder - C:\Program Files (x86)\Microsoft Visual Studio\Shared\Visual Studio Tools for Office\PIA\Office15\Office.dll 

This assembly was compiled against .NET runtime 2.0.50727.
This can be added from the Reference Manager, Assemblies, Extensions tab.
This can be accessed in code using the following namespace.

Office = Microsoft.Office.Core 

5) What is the Microsoft.Office.Core namespace/reference used for ?
This namespace contains the core objects that are shared across all the different Office 365 applications.
This file is not a Primary Interop Assembly and is just a COM Type Library.
The latest assembly for Office 365 can be found in this folder

Folder - C:\WINDOWS\assembly\GAC_MSIL\Office\15.0.0.0__71e9bce111e9429c\Office.dll 

This can be added from the Reference Manager, COM, Type Libraries tab.
This can be accessed in code using the following namespace.

Office = Microsoft.Office.Core 

If you want to access the latest object model, this is the latest file and should be used instead of the 2013 "Office.dll" PIA file that Visual Studio uses by default.

6) What is the MSO.dll file used for ?
This file contains Microsoft Office Components that are shared across Excel, Word, Outlook, and PowerPoint, such as user interface (UI) rendering, registry management, threading, and basic internet connections.

Folder - C:\Program Files\Microsoft Office\Root\VFS\ProgramFilesCommonX86\Microsoft Shared\Office16\MSO.dll 
Folder - C:\Program Files (x86)\Common Files\Microsoft Shared\Office15\MSO.DLL 

7) Have any good books been written on Visual Studio Tools for Office ?
Yes. Here is a list of books we would recommend:

2009 Feb - Visual Studio Tools for Office 2007: VSTO for Excel, Word and Outlook (Office 2007, Visual Studio 2008) 
2006 Dec - VSTO for Mere Mortals: A VBA Developers Guide (Office 2003, Visual Studio 2005) 
2006 Apr - Visual Studio Tools for Office Using Visual Basic 2005 with Excel, Word, Outlook (Office 2003, Visual Studio 2005) 
2005 Sep - Visual Studio Tools for Office Using C# with Excel, Word, Outlook (Office 2003, Visual Studio 2005) 

8) How many different versions of Visual Studio supported VSTO Add-ins ?