Semi-fix for Firefox code Copy and Paste

The underlieing problem is that Firefox ignores the css 'white-space:pre'
rule when actually copying and pasting. This Javascript turns newlines
into <br /> tags inside the code containers.

This will run in Safari, Opera, Chrome, Webkit, etc. gracefully.
This will not run in IE due to IE not having the methods needed.

A permanent solution would be at the Markdown level in such a way that
the highlighter still runs on the output with brake tags.

railties/guides/files/javascripts/guides.js

 function guideMenu(){
-
   if (document.getElementById('guides').style.display == "none") {
     document.getElementById('guides').style.display = "block";
   } else {
     document.getElementById('guides').style.display = "none";
   }
 }
+
+// Fix Copy+Paste of Code blocks in Firefox 3
+if ( window.addEventListener && document.getElementsByClassName ) {
+  window.addEventListener('load', function() {
+    var list = document.getElementsByClassName('code_container');
+    for (var i=0, len=list.length; i<len; i++) {
+      list[i].innerHTML = list[i].innerHTML.replace(/\n/g, '<br />');
+    }
+  }, false);
+}