Try using the IVsFileChangeEx service, like this:
IVsFileChangeEx fileChange =
(IVsFileChangeEx)host.GetService(typeof(SVsFileChangeEx));
fileChange.SyncFile(fileName);

Signature
José Escrich
http://latincoder.com
> Hi,
>
> How can I display the "This file has been modified outside of the source
> editor. Do you want to reload it?" message box in my implementation of
> IVsFileChangeEvents.FilesChanged?