Asked via another topic - how to do the above for 'some' categories. Do the following:
Identify the IDs of the categories you wish to have collapsed - the ID is in the URL for the category when you hover the mouse of the link for the category. Then...
Edit forums -> front -> index -> index
Find:
<li data-categoryID='{$category->_id}' class='cForumRow ipsBox ipsSpacer_bottom ipsResponsive_pull'>
Change to:
{{$collapseThese = array();}}
<li data-categoryID='{$category->_id}' class='cForumRow ipsBox ipsSpacer_bottom ipsResponsive_pull {{if \in_array($category->_id,$collapseThese)}}cForumRow_hidden' data-hidden="true"{{endif}}'>
Then populate the array() with the IDs of the categories:
{{$collapseThese = array(1,3,5,9,11);}}
Save the template.
User action of toggling the category open/closed will override this
That contains code that would collapse all the categories - to do 'some' you could wrap things in a check for the category ID. And then you have to account for 'first time' too (actually, not relevant...the user's own toggle action dictates from then on)
{$category->_id}
Will add some code to the other topic.