title: Window.addcloseHandler and Window.addwindowClosingHandler not disctinguishes between browser close and browser refresh event
body: <p>I am using GWT and in my application, I want to clear session history and forcefully logout user on the closing browser. But on click of refresh, the user should be logged in. I have written the following code for the same. </p>
  
  <pre><code>Window.addCloseHandler(new CloseHandler&lt;Window&gt;() {
      @Override
      public void onClose(CloseEvent&lt;Window&gt; event) {
          logoutRPC();
      }
  });
  
  Window.addWindowClosingHandler(new Window.ClosingHandler() {
      public void onWindowClosing(Window.ClosingEvent closingEvent) {
          logoutRPC();
      }
  });
  </code></pre>
  
  <p>But from both of the above, I am not able to achieve the functionality as refresh calls <code>GWT.closeHandler()</code>.</p>
  
  <p>How can I distinguish between both events?</p>