src/Tools/jEdit/src/debugger_dockable.scala

 import isabelle._
 
 import java.awt.{BorderLayout, Dimension}
 import java.awt.event.{ComponentEvent, ComponentAdapter, KeyEvent, MouseEvent, MouseAdapter}
 import javax.swing.{JTree, JScrollPane}
-import javax.swing.tree.{DefaultMutableTreeNode, TreeSelectionModel}
+import javax.swing.tree.{DefaultMutableTreeNode, DefaultTreeModel, TreeSelectionModel}
 import javax.swing.event.{TreeSelectionEvent, TreeSelectionListener}
 
 import scala.swing.{Button, Label, Component, SplitPane, Orientation}
 import scala.swing.event.ButtonClicked
 

       pretty_text_area.update(new_snapshot, Command.Results.empty, Pretty.separate(new_output))
 
     current_snapshot = new_snapshot
     current_threads = new_threads
     current_output = new_output
-
-    revalidate()
-    repaint()
   }
 
 
   /* tree view */
 

   tree.getSelectionModel.setSelectionMode(TreeSelectionModel.SINGLE_TREE_SELECTION)
 
   private def update_tree(entries: List[Debugger_Dockable.Tree_Entry])
   {
     tree.clearSelection
+    val tree_model = tree.getModel.asInstanceOf[DefaultTreeModel]
 
     root.removeAllChildren
     val entry_nodes = entries.map(entry => new DefaultMutableTreeNode(entry))
     for (node <- entry_nodes) root.add(node)
 
+    tree_model.reload(root)
     for (i <- 0 until tree.getRowCount) tree.expandRow(i)
 
     for ((entry, node) <- entries zip entry_nodes) {
       for (debug_state <- entry.debug_states) {
         val sub_node = new DefaultMutableTreeNode(debug_state.function)
         node.add(sub_node)
       }
     }
+    tree_model.reload(root)
 
     tree.revalidate()
   }
 
   private def action(node: DefaultMutableTreeNode)