allocate them temporarily, disposing of them
    automatically. The <code>with-ns-rect</code> macro (in
    the <code>NS</code> package) creates an <code>NSRect</code> value,
    and then disposes of it when control leaves the scope of the
    macro; for example:</p>

    <pre>
(ns:with-ns-rect (r 100 100 400 300)
   ...)
    </pre>

    <p>We can use this rectangle to initialize the shape of our new
    window:</p>

    <pre>
(ns:with-ns-rect (r 100 100 400 300)
   (#/initWithContentRect:styleMask:backing: