src/Tools/jEdit/src/isabelle_sidekick.scala

     val data = Isabelle_Sidekick.root_data(buffer)
 
     try {
       var offset = 0
       for (chunk <- Bibtex.parse(JEdit_Lib.buffer_text(buffer))) {
-        val n = chunk.size
+        val n = chunk.source.size
         chunk match {
           case item: Bibtex.Item if item.is_wellformed =>
             val label = if (item.name == "") item.kind else item.kind + " " + item.name
             val asset = new Isabelle_Sidekick.Asset(label, offset, offset + n)
             data.root.add(new DefaultMutableTreeNode(asset))