internal void FilesUpdate()
 {
     if (PropertyChanged == null)
     {
         return;
     }
     // todo: understand why RelayCommand does not need the changeshappened.
     // probably to do with CanExecuteChanged
     Verify.ChangesHappened();
     VerifyAndSave.ChangesHappened();
     SaveBimToCobie.ChangesHappened();
 }