ImageDraw::operator Image() const
{
	// ... a lot of code omitted here ...
	if(has_alpha) {
		xim = XGetImage(Xdisplay, alpha.dw, 0, 0, size.cx, size.cy, AllPlanes, ZPixmap);
		if(xim){    // added this check
			const byte *s = (const byte *)xim->data;
			t = ib;
			Buffer<RGBA> line(size.cx);
			for(int y = 0; y < size.cy; y++) {
				fmt.Read(line, s, size.cx, palette);
				for(int x = 0; x < size.cx; x++)
					(t++)->a = line[x].r;
				s += xim->bytes_per_line;
			}
			XDestroyImage(xim);
		}
	}
	Premultiply(ib);
	return ib;
}