code: function(eventArgs) {
                  if (eventArgs.kind === Windows.ApplicationModel.Activation.ActivationKind.pickSaveFileContinuation) {
                      var file = eventArgs.file;
                      saveFile(file);
                      webUIApp.removeEventListener("activated", fileSaveHandler);
                  }
              }
docs: /*
  Need to add and remove an event listener to catch activation state
  Using FileSavePicker will suspend the app and it's required to catch the pickSaveFileContinuation
  https://msdn.microsoft.com/en-us/library/windows/apps/xaml/dn631755.aspx