diff --git a/copyparty/web/md.js b/copyparty/web/md.js
index 68b0a6a5..d81c8aef 100644
--- a/copyparty/web/md.js
+++ b/copyparty/web/md.js
@@ -184,11 +184,19 @@ function md_plug_err(ex, js) {
     errbox.setAttribute('id', 'md_errbox');
     errbox.style.cssText = 'position:absolute;top:0;left:0;padding:1em .5em;background:#2b2b2b;color:#fc5'
     errbox.textContent = msg;
+    errbox.onclick = function () {
+        alert('' + ex.stack);
+    };
     if (o) {
         errbox.appendChild(o);
         errbox.style.padding = '.25em .5em';
     }
     dom_nav.appendChild(errbox);
+
+    try {
+        console.trace();
+    }
+    catch (ex2) { }
 }
 
 
@@ -338,7 +346,7 @@ function convert_markdown(md_text, dest_dom) {
     }
 
     ext = md_plug['post'];
-    if (ext)
+    if (ext && ext[0].render)
         try {
             ext[0].render(md_dom);
         }
@@ -347,6 +355,14 @@ function convert_markdown(md_text, dest_dom) {
         }
 
     copydom(md_dom, dest_dom, 0);
+
+    if (ext && ext[0].render2)
+        try {
+            ext[0].render2(dest_dom);
+        }
+        catch (ex) {
+            md_plug_err(ex, ext[1]);
+        }
 }
 
 
diff --git a/srv/extend.md b/srv/extend.md
index fd25a8e4..ab8c2f6f 100644
--- a/srv/extend.md
+++ b/srv/extend.md
@@ -18,6 +18,8 @@ this one becomes a hyperlink to ./except/ thanks to
 
 it is a passthrough to the markdown extension api, see https://marked.js.org/using_pro
 
+in addition to the markdown extension functions, `ctor` will be called on document init
+
 
 ### these/
 and this one becomes ./except/these/
@@ -36,6 +38,13 @@ whic hshoud be ./except/also-this.md
 # ok
 now for another extension type, `copyparty_post` which is called to manipulate the generated dom instead
 
+`copyparty_post` can have the following functions, all optional
+* `ctor` is called on document init
+* `render` is called when the dom is done but still in-memory
+* `render2` is called with the live browser dom as-displayed
+
+## post example
+
 the values in the `ex:` columns are linkified to `example.com/$value`
 
 | ex:foo       | bar      | ex:baz |
@@ -43,6 +52,8 @@ the values in the `ex:` columns are linkified to `example.com/$value`
 | asdf         | nice     | fgsfds |
 | more one row | hi hello | aaa    |
 
+and the table can be sorted by clicking the headers
+
 the difference is that with `copyparty_pre` you'll probably break various copyparty features but if you use `copyparty_post` then future copyparty versions will probably break you
 
 
@@ -123,5 +134,8 @@ render(dom) {
             }
         }
     }
+},
+render2(dom) {
+    window.makeSortable(dom.getElementsByTagName('table')[0]);
 }
 ```