Ooops. Forget it. I must study more. Here's the code I got to work.
using (Database db = new Database(false, true))
{
db.ReadDwgFile(sSourceFullFileName, FileOpenMode.OpenForReadAndReadShare, false, "");
// closing the input makes sure the whole dwg is read from disk
// it also closes the file so you can SaveAs the same name
db.CloseInput(true);
// store the current working database, to reset
Database currDb = HostApplicationServices.WorkingDatabase;
// set working database
HostApplicationServices.WorkingDatabase = db;
// { Do Some Work}
db.SaveAs(sFullDestFileName, DwgVersion.Current);
// reset the working database
HostApplicationServices.WorkingDatabase = currDb;
}
I picked it up in a desperate search in the forums...