interface IButton
{
    void Paint();
}

interface IGUIFactory
{
    IButton CreateButton();
}

class WinFactory : IGUIFactory
{
    public IButton CreateButton()
    {
        return new WinButton();
    }
}

class OSXFactory : IGUIFactory
{
    public IButton CreateButton()
    {
        return new OSXButton();
    }
}

class WinButton : IButton
{
    public void Paint()
    {
        //Render a button in a Windows style
    }
}

class OSXButton : IButton
{
    public void Paint()
    {
        //Render a button in a Mac OS X style
    }
}

class Program
{
    static void Main()
    {
        var appearance = Settings.Appearance;

        IGUIFactory factory;
        switch (appearance)
        {
            case Appearance.Win:
                factory = new WinFactory();
                break;
            case Appearance.OSX:
                factory = new OSXFactory();
                break;
            default:
                throw new System.NotImplementedException();
        }

        var button = factory.CreateButton();
        button.Paint();
    }
}