WindowViewModel.cs

// ViewModelBase.cs
    public class ViewModelBase : INotifyPropertyChanged
    {
        #region Implementation of INotifyPropertyChanged

        public event PropertyChangedEventHandler PropertyChanged;

        protected virtual void OnPropertyChanged([CallerMemberName] String propertyName = null)
        {
            if (PropertyChanged != null)
                PropertyChanged(this, new PropertyChangedEventArgs(propertyName));
        }

        protected virtual void OnPropertyChanged(PropertyChangedEventArgs eventArgs)
        {
            if (PropertyChanged != null)
                PropertyChanged(this, eventArgs);
        }

        #endregion
    }




// WindowViewModel.cs
    public class WindowViewModel : ViewModelBase
    {
        private Window _window;

        public WindowViewModel()
        {
            Window = new Window();
        }

        public WindowViewModel(IntPtr handle)
            : this()
        {
            Handle = handle;
        }

        public WindowViewModel(Int32 handle)
            : this(new IntPtr(handle))
        {
        }

        [Browsable(false)]
        public Window Window
        {
            get { return _window; }
            set
            {
                _window = value;
                Refresh();
            }
        }

        public String Title
        {
            get { return _window.Title; }
            set { _window.Title = value; OnPropertyChanged(); }
        }

        public Boolean IsTopmost
        {
            get { return _window.IsTopmost; }
            set { _window.IsTopmost = value; OnPropertyChanged(); }
        }

        public Int32 X
        {
            get { return _window.Rectangle.X; }
            set { _window.Rectangle = _window.Rectangle.Modify(newX: value); OnPropertyChanged(); }
        }

        public Int32 Y
        {
            get { return _window.Rectangle.Y; }
            set { _window.Rectangle = _window.Rectangle.Modify(newY: value); OnPropertyChanged(); }
        }

        public Int32 Width
        {
            get { return _window.Rectangle.Width; }
            set { _window.Rectangle = _window.Rectangle.Modify(newWidth: value); OnPropertyChanged(); }
        }


        public Int32 Height
        {
            get { return _window.Rectangle.Height; }
            set { _window.Rectangle = _window.Rectangle.Modify(newHeight: value); OnPropertyChanged(); }
        }

        public IntPtr Handle
        {
            get { return _window.Handle; }
            set
            {
                if (_window.Handle == value)
                    return;
                _window.Handle = value;
                Refresh();
            }
        }

        public void Refresh()
        {
            OnPropertyChanged(new PropertyChangedEventArgs("Window"));
            OnPropertyChanged(new PropertyChangedEventArgs("Handle"));
            OnPropertyChanged(new PropertyChangedEventArgs("Title"));
            OnPropertyChanged(new PropertyChangedEventArgs("Rectangle"));
            OnPropertyChanged(new PropertyChangedEventArgs("Icon"));
            OnPropertyChanged(new PropertyChangedEventArgs("IsTopmost"));
        }
    }