New Rad Studio 10.3 User Question -- Problem with "Starting your first RAD Studio application Index (IDE Tutorial) ".

As a completely new user to RAD Studio, I am working through an example provided by Embarcadero:

http://docwiki.embarcadero.com/RADStudio/Rio/en/Starting_your_first_RAD_Studio_application_Index_(IDE_Tutorial)

I am using C++ Builder for the tutorial.

As I reach the stage in the tutorial here:

http://docwiki.embarcadero.com/RADStudio/Rio/en/Coding_responses_to_user_actions_in_the_Code_Editor_(IDE_Tutorial)

The member function as follows is inserted into the TextEditorUnit.cpp code:

void __fastcall TTextEditorForm::SaveAsExecute(TObject *Sender)
{
    if (TextEditorForm->SaveFileDialog->Execute()) {
        String FileName = TextEditorForm->SaveFileDialog->FileName;
        if (FileExists(FileName)) {
            String UserResponse = TDialogServiceSync::MessageDialog(L"File already exists. Do you want to overwrite?", TMsgDlgType::mtInformation, mbYesNo, TMsgDlgBtn::mbYes, 0);
            if (UserResponse == System::Uitypes::TMsgDlgBtn::mbNo) {
                return;
            }
        }
        TextEditorForm->Editor->Lines->SaveToFile(FileName);
        CurrentFile = FileName;
        Caption = L"Text Editor - " + ExtractFileName(FileName);
    }
}

The concern is that the TDialogServiceSync is not declared : (use of undeclared identifier.  'TDialogServiceSync ')

Am I missing something?  There appears to be a problem with this tutorial. 

Perhaps I am working from a database of examples that have not been updated?  Or could it be that I have not installed correctly?