How to instantiate my C++ class from QtScript? My class inherits QObject

Question

I am researching possibilities of QtScript. I understand that it is possible to create QObject in C++ and then pass it into QScriptEngine:

QObject *someObject = new WindowWithText;
QScriptValue objectValue = engine.newQObject(someObject);
engine.globalObject().setProperty("window", objectValue);

This works - I was able to call my methods defined in C++:

WindowWithText declaration:

#include <QWidget>

namespace Ui {
class WindowWithText;
}

class WindowWithText : public QWidget
{
  Q_OBJECT

public:
  explicit WindowWithText(QWidget *parent = 0);
  ~WindowWithText();
public slots:
  void setHeading(const QString&);
  void setContents(const QString&);
  QString getHeading() const;

private:
  Ui::WindowWithText *ui;
};

But I would like to instantiate windows from qtscript itself, like this:

var window = new WindowWithText();

I understand I will probably have to write some proxy between constructor and QtCcript, but how to do it?

So far, I just created static method newInstance that creates the object, but that's no new:

QScriptValue WindowWithText::newInstance(QScriptContext *context, QScriptEngine *engine)
{
  QObject *someObject = new WindowWithText;
  QScriptValue objectValue = engine->newQObject(someObject);
  return objectValue;
}

I exported it to the engine as follows:

engine.globalObject().setProperty("WindowWithText", engine.newFunction(WindowWithText::newInstance));

This does not use new though and isn't true javascript pseudoclass:

Following code will fail:

function Subclass() {
  this.setHeading("bla bla");
}
Subclass.prototype = Object.create(WindowWithText.prototype);

var window = new dd();
window.show();

Error caused by the fact that WindowWithText.prototype doesn't have anything to do with WindowWithText:

TypeError: Result of expression 'this.setHeading' [undefined] is not a function.

Is there more reliable and less tedious way of exporting C++ classes to my engine?