make sure click-once knows about the file (it is listed in the .exe.manifest) and will be distributed with the exe

int main(array<System::String ^> ^args){
    System::IO::Stream^ st = System::IO::File::OpenRead(".\\window1.xaml");
    Window^ mainwnd = (Window^)System::Windows::Markup::XamlReader::Load(st);
    mainwnd->Height = 400;
    mainwnd->Width = 600;
    mainwnd->Title = "Dynamically load Xaml";
    //FindName will find the element with the specified identifier
    Button^ btn = (Button^)mainwnd->FindName("mButton");
    btn->Click += gcnew RoutedEventHandler(&EventHelper::OnBtnClick);
    st->Close();
    return (gcnew Application())->Run(mainwnd);

}

ref struct EventHelper
{
    static void OnBtnClick(Object^ sender, RoutedEventArgs^ e)
    {
        Window^ mainwnd = Application::Current->MainWindow;
        TextBox^ txtbox = (TextBox^)mainwnd->FindName("mTextBox");
        mainwnd->Title = txtbox->Text;
    }
};