Add additional column classes to Genesis Widget Column Classes plugin.

custom-genesis-widget-column-classes.php

<?php // Do not include this line.

add_filter( 'genesis_widget_column_classes', 'custom_widget_column_classes' );
/**
 * Custom column widths.
 *
 * Adds additional column classes to Genesis Widget Column Classes plugin
 * including fifths and full-width classes.
 *
 * @return array
 */
function custom_widget_column_classes() {

	$column_classes = array(
    		'full-width'    => 'full-width',
		'one-half'      => 'one-half',
		'one-third'     => 'one-third',
		'one-fourth'    => 'one-fourth',
		'one-fifth'     => 'one-fifth',
		'one-sixth'     => 'one-sixth',
		'two-thirds'    => 'two-thirds',
		'two-fourths'   => 'two-fourths',
		'two-fifths'    => 'two-fifths',
		'two-sixths'    => 'two-sixths',
		'three-fourths' => 'three-fourths',
		'three-fifths'  => 'three-fifths',
		'three-sixths'  => 'three-sixths',
		'four-fifths'   => 'four-fifths',
		'four-sixths'   => 'four-sixths',
		'five-sixths'   => 'five-sixths',
	);

	return $column_classes;

}