You didn't say that you wanted that - try the built-in case 2:
PHP Code:
      case 2://active only  (per level when no cat selected)
        
if($cPath_top == 0){//test
          
$test_level 1;
          break;
        }
        if(
$cPath_top != $path_top$skip_cat 1;
        break; 
define('CAT_BOX_ACTIVE_LEVEL', '2|0|0');//full active tree only; only top cats when no cat selected

If what you want is to have no top cats showing when one is selected, you could modify case 2:
PHP Code:
      case 2://active only, without top  (per level when no cat selected)
        
if($cPath_top == 0){//test
          
$test_level 1;
          break;
        }
        if(
$cPath_top != $path_top or $path == $path_top$skip_cat 1;
        break;