:	PaintCanvas(hwnd), BufferedCanvas(hdc, 0, 0, rcPaint.right, rcPaint.bottom) {}
:	PaintCanvas(hwnd), BufferedCanvas(PAINTSTRUCT::hdc, 0, 0, rcPaint.right, rcPaint.bottom) { }
	BufferedPaintCanvas(HWND hwnd)	 :	PaintCanvas(hwnd), BufferedCanvas(hdc, 0, 0, rcPaint.right, rcPaint.bottom) {}