public void OnClosing(ViewModelClosingEventArgs e)
{
var handler = Closing;
if (handler != null) handler(this, e);
}
protected virtual bool RaiseClosing(object parameter)
{
var handler = Closing;
if (handler == null)
return true;
var args = new ViewModelClosingEventArgs(this, parameter);
handler(this, args);
return !args.Cancel;
}