WordPress at a glance
filter is not described

is_wide_widget_in_customizer filter-hook . WP 3.9.0

Filters whether the given widget is considered "wide".

Usage

add_filter( 'is_wide_widget_in_customizer', 'filter_function_name_8300', 10, 2 );
function filter_function_name_8300( $is_wide, $widget_id ){
	// filter...

	return $is_wide;
}
$is_wide(true/false)
Whether the widget is wide, Default false.
$widget_id(string)
Widget ID.

Where the hook is called

WP_Customize_Widgets::is_wide_widget()
is_wide_widget_in_customizer
wp-includes/class-wp-customize-widgets.php 577
return apply_filters( 'is_wide_widget_in_customizer', $is_wide, $widget_id );

Where the hook is used (in WP core)

Does not used.