lass="arg-name">customizations</code> whereever a property list is expected.</p>

<div class="api_docstring">
  <p class="api">[macro]
<code class='api'><span class='api-name'>with-shadowed-custom-vars</span>
<span class='lambda-kwd'>&amp;body</span>
<span class='arg-name'>body</span>
</code>
  </p>
<p class="docstring">Execute <code class="arg-name">body</code> in a dynamic environment where the names of all existing customization parameters are re-bound to fresh locations.  The initial values of the param