#2 Sep 30, 2011 19:17
First of all, are you editing a plugin or a widget from /inc/widgets/widgegts/_coll_category_list.widget.php ? It's not the same, you shouldn't work on existing widgets if you want to create a plugin.
Pick a plugin that provides a widget, like the one I released yesterday
See how it works, in SkinTag() method you use $params['my_param'] instead of $this->disp_params['my_param']