Example of fpw_widget_templates filter in Feature a Page Widget 2.0. Allows remove of default layouts, "registering" of custom layouts, or setting one layout for all widget instances.

fpw_widget_templates_filter_examples.php

<?php
/**
 * remove a default template
 * 
 * default templates are: big, banner, wrapped
 * 
 * this example removes the "Big Image" template
 * 
 * @param	$templates	array	slug => label pairs of templates
 */
function fpw_remove_widget_template( $templates ) {
	unset( $templates['big'] );
	return $templates;
}
add_filter( 'fpw_widget_templates', 'fpw_remove_widget_template' );
 
/**
 * add a custom template
 * 
 * In addition to this filter, you must create a file named my_new_template.php in a /fpw2_views/ folder in the active child or parent theme
 * 
 * @param	$templates	array	slug => label pairs of templates
 */
function fpw_add_widget_template( $templates ) {
	$templates['my_new_template'] = __( 'My New Template', 'your-text-domain' );
	return $templates;
}
add_filter( 'fpw_widget_templates', 'fpw_add_widget_template' );

/**
 * add one layout for all widgets (& remove Layout setting)
 *
 * Example sets widget to always use the "Banner" layout
 * 
 * @param	$templates	array	slug => label pairs of templates
 */
function fpw_set_widget_template() {
  $template = array( 'banner' => 'Banner Image' ); // note array length = 1
  return $template;
}
add_filter( 'fpw_widget_templates', 'fpw_set_widget_template' );