package flask using node-webkit

loading.html

You can create a loading page and render the actual app after the web server has started.

The loading page (loading.html) will load a js file that launches your actual application page as a hidden window and you can then show it when the server is running.

<script>
var currentWindow = gui.Window.get(); // Get reference to loading.html

var exec = require('child_process').execFile;
exec('home.py', {cwd:'.'}, function (error, stdout, stderr){ // Runs your python code
  var appWindow = gui.Window.open('app.html', // Starts your application
    { width: 800,
      height: 600,
      position: 'center',
      focus: false,
      transparent: true // This hides the application window
    }
);
appWindow.on('loaded', function() { // Waits for application to be loaded
  currentWindow.close({force: 'true'}); // Closes loading.html
    appWindow.show();  // Shows app.html
    appWindow.focus(); // Set the focus on app.html
  });
});

	
</script>

Anyway that is the gist of it, but you may need to make changes for your particular setup. Hope it helps.

package.json

{
  "name": "pythonApp",
  "version": "0.0.0",
  "main": "loading.html",
  "window": {
    "title": "App Name",
    "width": 800,
    "height": 600,
    "position": "center",
  }
}