Lost in the woods, dropping breadcrumbs as they go...

Gretel.fwaction

<action-encoding>UTF-8</action-encoding>
<page-action name="com.wdstudio.gretel" title="Gretel">
<action-version version="0.1">
Gretel
Copyright 2013 Walter Lee Davis

Add trailing comments to each block-level tag.
</action-version>
<action-javascript>
function fwAfterEndBody(){
  var tags = fwDocument.fwTags.fwFindAll(['div','article','section','aside','header','footer', 'nav', 'address']);
  for (var i = tags.length - 1; i >= 0; i--){
    var tag = tags[i];
    if(tag.id){
      var id = tag.id.toString().slice(1,-1);
      var dummy = tag.fwAddEnclosing('');
      dummy.fwAddRaw('<!-- end ' + id + ' -->');
    }
  };
}
</action-javascript>
</page-action>