title: Get logged in user's name from process running under "run as" credentials
body: <p>One can run exe as user different from currently logged in one (using "run as").</p>
  
  <p>For example I log in as "user1" into Windows and start executable with "run as" using credentials of "User2".</p>
  
  <p>How to retreive user name/identity of "User1" (who logged in currently) and not "User2" (which the process runs under)?</p>
  
  <p>I.e. <code>System.Environment.UserName</code> give User2 (as expected).</p>