public function editor_css_files() {
        $files = array();

        // First editor plugins.
        $plugins = core_component::get_plugin_list('editor');
        foreach ($plugins as $plugin=>$fulldir) {
            $sheetfile = "$fulldir/editor_styles.css";
            if (is_readable($sheetfile)) {
                $files['plugin_'.$plugin] = $sheetfile;
            }
        }
        // Then parent themes - base first, the immediate parent last.
        foreach (array_reverse($this->parent_configs) as $parent_config) {
            if (empty($parent_config->editor_sheets)) {
                continue;
            }
            foreach ($parent_config->editor_sheets as $sheet) {
                $sheetfile = "$parent_config->dir/style/$sheet.css";
                if (is_readable($sheetfile)) {
                    $files['parent_'.$parent_config->name.'_'.$sheet] = $sheetfile;
                }
            }
        }
        // Finally this theme.
        if (!empty($this->editor_sheets)) {
            foreach ($this->editor_sheets as $sheet) {
                $sheetfile = "$this->dir/style/$sheet.css";
                if (is_readable($sheetfile)) {
                    $files['theme_'.$sheet] = $sheetfile;
                }
            }
        }

        return $files;
    }