test

<?php
function ding_facetbrowser_theme() {
  return array(
   'facetbrowser' => array(
     'variables' => array(
       'facets'    => NULL,
       'searchkey' => NULL,
     ),
    ),
  );
}

function theme_facetbrowser($all_facets = FALSE, $search_key =NULL ) {
  error_log(print_r($search_key,1));
  // $search_key = NULL here
  }
}

function ding_facetbrowser_block_view($delta = FALSE) {
  ...............
  $results = module_invoke($executed_search_module, 'ding_facetbrowser');
  // $results->searchkey = 'zorro' here
  $block_content = theme('facetbrowser', $results->facets, $results->searchkey);
  ...............
  return $block;
}