Форуми / Cotonti / Support / How to show all categories and its sub categories in the list?

Not clearly understand what you speak about…  Trying to answer anyway.

You had one `catlist.tpl` tpl placed in `themes/plugins`. (see it below). Than you put TPL callback in your dropdown menu code (in `header.tpl` or wherever it had been placed):

{PHP|catlist('catlist',0,'','root_category_name')}

or 

{CAT_NAME|catlist('catlist',0,'','$this')}

catlist,tpl:

<!-- BEGIN: MAIN -->
<div class="dropdown">
	<ul class="dropdown-menu custom" role="menu" aria-labelledby="dropdownMenu_{CAT_TITLE}">
<!-- BEGIN: CAT_ROW -->
		<li class="subitem" role="presentation"><a role="menuitem" tabindex="-1" href="{cat_name|cot_url('page','c=$this')}">{CAT.title} </a></li>
<!-- END: CAT_ROW -->
</ul>
</div>
<!-- END: MAIN -->