Add class to Categories Widget

Here is a little jQuery snippet I made that should do what you want it to do (this just works for the category widget):

// JavaScript Document
$j = jQuery.noConflict();
$j(document).ready(function(){
    $j('li.cat-item-1').parent().addClass('test');
});

If you wanted to do this to all widgets, well it depends on the parent element of the widgets. Let’s say there’s a <div class="widget"></div> wrapping each widget. You could do this to add the class to immediate child <ul>‘s of all widgets:

// JavaScript Document
$j = jQuery.noConflict();
$j(document).ready(function(){
    $j('.widget > ul').addClass('test');
});

However with PHP, that’s a different story.