Add In. Form Region Factory Resolve Event
Occurs when the add-in loads, and when a form region name that is specified in the registry does not match the name of any form regions defined in the add-in.
event Microsoft.Office.Tools.Outlook.FormRegionFactoryResolveEventHandler FormRegionFactoryResolve;
You can use this event to supply one or more form regions when the add-in loads. You must describe a form region in the registry. For more information about form region registry entries, see Registry Entries for VSTO Add-ins.
Ensure that the name that you specify in the registry must not match the name of any form regions defined in the add-in.