Small code improvement

program/js/app.js

@@ -1134,8 +1134,8 @@ function rcube_webmail()
           this.gui_objects.messagepartframe.contentWindow.print();
         }
         else if (uid = this.get_single_uid()) {
-          this.printwin = this.open_window(this.env.comm_path+'&_action=print&_uid='+uid+'&_mbox='+urlencode(this.get_message_mailbox(uid))+(this.env.safemode ? '&_safe=1' : ''), true, true);
-          if (this.printwin) {
+          url = '&_action=print&_uid='+uid+'&_mbox='+urlencode(this.get_message_mailbox(uid))+(this.env.safemode ? '&_safe=1' : '');
+          if (this.open_window(this.env.comm_path + url, true, true)) {
             if (this.env.action != 'show')
               this.mark_message('read', uid);
           }