 shown (default is <code>0</code>)
</td></tr><tr valign="top"><td valign="baseline" nowrap><i>end</i></td><td valign="baseline">&nbsp;&nbsp;&nbsp;&nbsp;</td><td valign="baseline"> An integer specifying the last <a href="ref-glossary.html#id188">queue&nbsp;element</a> to
be shown or <code>nil</code> indicating that the last <a href="ref-glossary.html#id188">queue&nbsp;element</a> is
to be shown (default is <code>nil</code>) 
</td></tr><tr valign="top"><td valign="baseline" nowrap><i>show-element-function</i>