WordPress at a glance
filter is not described

editor_stylesheets filter-hook . WP 4.3.0

Filters the array of stylesheets applied to the editor.

Usage

add_filter( 'editor_stylesheets', 'filter_function_name_7017' );
function filter_function_name_7017( $stylesheets ){
	// filter...

	return $stylesheets;
}
$stylesheets(array)
Array of stylesheets to be applied to the editor.

Where the hook is called

get_editor_stylesheets()
editor_stylesheets
wp-includes/theme.php 1923
return apply_filters( 'editor_stylesheets', $stylesheets );

Where the hook is used (in WP core)

Does not used.