@package: Listing

Method: Filter the main query listing by the course_id

Method: Group Selector Filter.

Method: Course Selector Filter.

Method: Output custom user column row data

Method: Show the User Courses column.

Method: Public constructor for class

Method: Called via the WordPress init action hook.

Method: Call via the WordPress load sequence for admin pages.

Method: Adds the user course filter in admin.

Method: This function fill filter the table listing items based on filters selected.

Method: Filter the main query listing by the group_id