Index: mail/em-format.c
===================================================================
--- mail/em-format.c	(revision 34224)
+++ mail/em-format.c	(working copy)
@@ -224,6 +224,38 @@ em_format_class_add_handler(EMFormatClas
 	g_hash_table_insert(emfc->type_handlers, info->mime_type, info);
 }
 
+struct _class_handlers {
+	EMFormatClass *old;
+	EMFormatClass *new;
+};	
+static void
+merge_missing (gpointer key, gpointer value, gpointer userdata)
+{
+	struct _class_handlers *classes = (struct _class_handlers *) userdata;
+	EMFormatHandler *info, *oldinfo;
+	
+	oldinfo = (EMFormatHandler *) value;
+	info = g_hash_table_lookup (classes->new->type_handlers, key);
+	if (!info) {
+		/* Might be from a plugin */
+		g_hash_table_insert (classes->new->type_handlers, key, value);
+	}
+
+}
+
+void
+em_format_merge_handler(EMFormat *new, EMFormat *old)
+{
+	EMFormatClass *oldc = (EMFormatClass *)G_OBJECT_GET_CLASS(old);
+	EMFormatClass *newc = (EMFormatClass *)G_OBJECT_GET_CLASS(new);
+	struct _class_handlers fclasses;
+
+	fclasses.old = oldc;
+	fclasses.new = newc;
+
+	g_hash_table_foreach (oldc->type_handlers, merge_missing, &fclasses);
+
+}
 /**
  * em_format_class_remove_handler:
  * @emfc: 
Index: mail/em-format.h
===================================================================
--- mail/em-format.h	(revision 34224)
+++ mail/em-format.h	(working copy)
@@ -328,5 +328,6 @@ void em_format_format_text(EMFormat *emf
 
 void em_format_part_as(EMFormat *emf, struct _CamelStream *stream, struct _CamelMimePart *part, const char *mime_type);
 void em_format_part(EMFormat *emf, struct _CamelStream *stream, struct _CamelMimePart *part);
+void em_format_merge_handler(EMFormat *new, EMFormat *old);
 
 #endif /* ! _EM_FORMAT_H */
Index: mail/em-folder-view.c
===================================================================
--- mail/em-folder-view.c	(revision 34224)
+++ mail/em-folder-view.c	(working copy)
@@ -2193,6 +2193,9 @@ em_folder_view_print (EMFolderView *emfv
 	em_format_set_session (
 		(EMFormat *) efhp,
 		((EMFormat *) emfv->preview)->session);
+	em_format_merge_handler ((EMFormat *) efhp,
+		(EMFormat *) emfv->preview);
+
 	em_format_html_print_message (
 		efhp, emfv->folder, uids->pdata[0]);
 	g_object_unref (efhp);