The Tree Filter Plugin
Plugin Name: treefilter
Purpose: The Tree Filter plugin allows users to filter calendar events by drilling down category levels when categories are configured in a tree layout. Up to 4 levels can be searched. It will also filter events when downloading an iCalendar file.
This plugin is similar to the Category Controller plugin. Both plugins provide filtering of events by category on a calendar, however, the tree filter plugin dynamically updates the calendar as each category level is chosen. The tree filter also works responsively when a responsive template is used, whereas the category controller does not. Typically, only one filter plugin will be enabled for a calendar.
Enable this plugin from the calendar's plugin tab. Select the top level category to filter. This plugin is useful only when categories are laid out in a tree structure.