title: MVVM Light ViewModelLocator: How to register Singleton ViewModel?
body: <p>I'm familiar with MVVM Light toolkit's ViewModelBase, Message, but not familiar with the ViewModelLocator. In my application there is Singleton ViewModel, such as PrinterViewModel. Registering is like</p>
  
  <pre><code>SimpleIoc.Default.Register&lt;IPrinter,PrinterViewModel&gt;();
  </code></pre>
  
  <p>When debugging, the error is something like 'Cannot register: No public constructor found'.</p>
  
  <p>So 2 questions:</p>
  
  <ol>
  <li>Is it bad idea to have Singleton ViewModel?</li>
  <li>How to register Singleton ViewModel, since I did not find any overloads to pass an instance for certain interface?</li>
  </ol>