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How Microsoft Project Finds the OnePager Pro Add-In

When OnePager Pro is run as a COM Add-In, it is vital that MS Project find the OnePager program when MS Project starts up. Otherwise, the buttons that launch OnePager will not appear on the toolbar. This FAQ gives a technical description of how this works. Everything happens in the Windows registry, and you can observe this registry information by running the Microsoft program regedit.

MS Project discovers OnePager by using the following key in the registry:

HIVE\Software\Microsoft\Office\MS Project\Addins\CG_MSP_Addin.OnePager

Where HIVE=HKCU for a per-user installation and HIVE=HKLM for a per-machine installations.

This key is placed in the registry during the OnePager installation process. Under this key, LoadBehavior=3 causes the OnePager buttons to appear every time MS Project is launched. LoadBehavior=2 means either that the user has disabled OnePager or that an error has occurred when MS Project attempted to load OnePager.

The string CG_MSP_Addin.OnePager is called the ProgID in Microsoft COM terminology. Once MS Project knows the ProgID, it looks in the registry to find the ClassID for OnePager Pro, which has the value {B3D82CD4-08B1-44CA-850C-C7869724CDE8}. Using this ClassID, MS Project retrieves the path to the binary files and executes them to place the buttons on the ribbon or toolbar.

Last Updated: December 27, 2019