protected SimpleViewModel()
{
_activatedCommand = new RelayCommand(p => OnWindowActivated());
_deactivatedCommand = new RelayCommand(p => OnWindowDeactivated());
_loadedCommand = new RelayCommand(p => OnWindowLoaded());
_unloadedCommand = new RelayCommand(p => OnWindowUnloaded());
_closeCommand = new RelayCommand(p => OnWindowClose());
}