Registry Entries

All VSTO add-ins require registry entries that specify the manifest name, manifest location and the load behavior of the add-in.


DescriptionString (REG_SZ)A brief description of the add-in. This is the name displayed to the user.
FriendlyNameString (REG_SZ)The descriptive name that is displayed in the COM add-ins dialog box. The default value is the add-in ID.
LoadBehaviorDWORD (REG_DWORD)The load behaviour of the add-in.
See the table below for a list of possible values.
ManifestString (REG_SZ)The full folder and filename of the application manifest. This must be a local path.

If you have Visual Studio 2010 Tools for Office Runtime SP1 installed on your development machine, you must add the prefix "file:///". If this prefix is not used and your add-in reads data from the application configuration file, users might receive an error when the add-in loads.

Introduced for Office 2007 to combine ManifestLocation and ManifestName.
ManifestLocationString (REG_SZ)(Office 2003 only)
C:\Program Files\Company\
The folder path of the application manifest. Only applicable for Office 2003.
ManifestNameString (REG_SZ)(Office 2003 only)
myaddin.dll.manifest
The file name of the application manifest. Only applicable for Office 2003.
WarmupDWORD (REG_DWORD)(Optional) Indicates that the .NET Framework and the VSTO Runtime load before an add-in loads. This reduces the perceved time to load. Set this value to 1. Only applicable for Outlook 2010 add-ins deployed using Windows Installer.

| vstolocal
If you are using Windows Installer to deploy your solution then appending "|vstolocal" tells the VSTO Runtime to run the solution from the location indicated by the manifest value and not loaded into the ClickOnce cache
Not including this postfix will cause the runtime to copy the customization into the ClickOnce cache.


If you are using a Setup project (ie Windows Installer) to deploy your solution you must append "|vstolocal" to the end of this path.
When a solution is built from Visual Studio then the "| vstolocal" is automatically added to the Manifest value.


LoadBehavior DWORD

This value describes the load behaviour of the COM Add-in.
This value can be a bitwise or of any of the following values

0Disconnected. The add-in is not loaded.
1Connected. The add-in is loaded.
2Load at Startup. The add-in will be loaded and connected when the host application starts.
8Load on Demand. The add-in will be loaded and connected when the host application requires it (for example when a user clicks a button that uses functionlaity in that add-in).
16Connect First Time. The add-in will be loaded and connected the first time the user runs the host application after registering the add-in.

Possible Values

0DisconnectedThe add-in is not loaded when the host application starts. It can be loaded from the COM Add-ins dialog box or programmatically, which sets the status to 1.
1ConnectedThe add-in is not loaded when the application starts. It can be loaded from the COM Add-ins dialog box or programmatically.
2DisconnectedThe add-in is loaded when the host application starts. Once the add-in is loaded it will always remain loaded until explicitely unloaded. Changing the status to 3
3ConnectedThe add-in is loaded when the host application starts. Once the add-in is loaded it will always remain loaded until explicitely unloaded.
8DisconnectedThe add-in is loaded and connected when the host application requires it. Changing the status to 9.
9ConnectedThe add-in is loaded and connected when the host application requires it.
16DisconnectedThe add-in loads when the user runs the host application for the first time, and it creates a button or menu item for itself. The next time the user starts the application, add-in is loaded on demand. Changing the status to 9.

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