src/Tools/jEdit/src/fold_handling.scala

         case that: Fold_Handler => true
         case _ => false
       }
 
     override def getFoldLevel(buffer: JEditBuffer, line: Int, seg: Segment): Int =
-      Token_Markup.buffer_line_depth(buffer, line)
+      Token_Markup.buffer_line_nesting(buffer, line).depth_before
   }
 
 
   /* output: static document rendering */