title: How are async void event handlers called in C#?
body: <p>If I declare my event handlers as <code>async void</code>, will they be called synchronously or asynchronously by the .NET framework?</p>
  
  <p>I.e., given the following code:</p>
  
  <pre><code>async void myButton_click(object sender, EventArgs e) {
     do stuff
     await longRunning()
     do more stuff
  }
  </code></pre>
  
  <p>Can I be sure that the "do stuff" line will be executed on the GUI thread?</p>