struct Window {
    private Framebuffer* fb;
    private size_t       startX;
    private size_t       startY;
    private size_t       _length;
    private size_t       _height;
    private uint*        _canvas;

    @property size_t length() { return _length; }
    @property size_t height() { return _height; }
    @property uint*  canvas() { return _canvas; }

    this(Framebuffer* f, size_t sx, size_t sy, size_t l, size_t h) {
        fb      = f;
        startX  = sx;
        startY  = sy;
        _length = l;
        _height = h;
        _canvas = newArray!(uint)(length * height);
    }

    ~this() {
        if (_canvas != null) {
            delArray(_canvas);
        }
    }

    void draw() {
        // Title bar.
        auto barStartY = startY - fontHeight;
        foreach (x; 0.._length) {
            foreach (y; 0..fontHeight) {
                fb.putPixel(startX + x, barStartY + y, windowBorder);
            }
        }
        plotString(fb, startX, barStartY, "Window", 0xFFFFFF);

        // Contents.
        foreach (x; 0.._length) {
            foreach (y; 0.._height) {
                fb.putPixel(startX + x, startY + y, canvas[x + length * y]);
            }
        }
    }
}