I used this I have x-cart 4
<FORM method="POST" action="search.php" name="showall">
<INPUT type="hidden" name="mode" value="search">
<INPUT type="hidden" name="posted_data[by_title]" value="Y">
<INPUT type="hidden" name="posted_data[by_shortdescr]" value="Y">
<INPUT type="hidden" name="posted_data[by_fulldescr]" value="Y">
<INPUT type="hidden" name="posted_data[substring]" size="16" value="">
Show all products{include file="buttons/search_head.tpl"}
</FORM>
I added it at the top of my site next to the drop down
http://www.pixellab.biz