title: Get elapsed time since application start
body: <p>I am porting an app from ActionScript3.0 (Flex) to C# (WPF).AS3.0 has got a handy utility called <a href="http://help.adobe.com/en_US/FlashPlatform/reference/actionscript/3/flash/utils/package.html#getTimer%28%29" rel="noreferrer">getTimer()</a> which returns time since Flash Virtual machine start in milliseconds.I was searching in C# through classes as</p>
  
  <pre><code>DateTime
  DispatcherTimer
  System.Diagnostics.Process
  System.Diagnostics.Stopwatch
  </code></pre>
  
  <p>but found nothing like this.It seems a very basic feature to me.For example Unity3D which runs on Mono has something familiar. Do I miss some utility here? </p>
  
  <p>Thanks in advance. </p>