--- loncom/homework/cleanxml/post_xml.pm	2016/01/20 00:40:39	1.8
+++ loncom/homework/cleanxml/post_xml.pm	2016/01/21 22:09:38	1.9
@@ -1,7 +1,7 @@
 # The LearningOnline Network
 # Third step to clean a file.
 #
-# $Id: post_xml.pm,v 1.8 2016/01/20 00:40:39 damieng Exp $
+# $Id: post_xml.pm,v 1.9 2016/01/21 22:09:38 damieng Exp $
 #
 # Copyright Michigan State University Board of Trustees
 #
@@ -128,6 +128,8 @@ sub post_xml {
   
   remove_useless_notsolved($root);
   
+  fix_comments($root);
+  
   fix_paragraphs_inside($root, \@all_block);
 
   remove_empty_style($root);
@@ -1809,6 +1811,25 @@ sub remove_useless_notsolved {
     }
   }
 }
+
+# Use <pre> for multi-line comments without elements.
+sub fix_comments {
+  my ($root) = @_;
+  my $doc = $root->ownerDocument;
+  my @comments = $root->getElementsByTagName('comment');
+  foreach my $comment (@comments) {
+    my $first = $comment->firstChild;
+    if (defined $first) {
+      if ($first->nodeType == XML_TEXT_NODE && $first->nodeValue =~ /\n/ &&
+          !defined $first->nextSibling) {
+        my $pre = $doc->createElement('pre');
+        $comment->removeChild($first);
+        $comment->appendChild($pre);
+        $pre->appendChild($first);
+      }
+    }
+  }
+}
 
 # adds a paragraph inside if needed and calls fix_paragraph for all paragraphs (including new ones)
 sub fix_paragraphs_inside {