title: Access Internal resource in vaadin with new browser window
body: <p>I'm working with vaadin, I want to generate a report when user click the button,My report is within the application,I want to open the report within new browser window. When I try to do that, it opens the window but shows the same window I'm currently in. I used "open()" method to open new window and to for the report path I used "ExternalResource". Here is my code</p>
  
  <pre><code>    mainWindow.getWindow().open(
                      new ExternalResource("http://localhost:8080/myapp/reports/report.rptdesigng"),
                      "_blank", // window name
                      500, // width
                      200, // weight
                      Window.BORDER_NONE // decorations
                      );
  </code></pre>