clarified tree row handling;

--- a/src/Tools/Graphview/tree_panel.scala	Tue Aug 11 21:36:25 2015 +0200
+++ b/src/Tools/Graphview/tree_panel.scala	Tue Aug 11 22:01:11 2015 +0200
@@ -159,7 +159,7 @@
       root.removeAllChildren
       for (node <- nodes) root.add(new DefaultMutableTreeNode(node))
 
-      for (i <- 0 until tree.getRowCount) tree.expandRow(i)
+      tree.expandRow(0)
       tree.revalidate()
     }
     revalidate()

--- a/src/Tools/jEdit/src/debugger_dockable.scala	Tue Aug 11 21:36:25 2015 +0200
+++ b/src/Tools/jEdit/src/debugger_dockable.scala	Tue Aug 11 22:01:11 2015 +0200
@@ -166,9 +166,8 @@
 
   private def update_tree(thread_entries: List[Debugger_Dockable.Thread_Entry])
   {
-    val old_thread_selection =
-      thread_selection() orElse
-      thread_entries.collectFirst { case t if t.debug_states.nonEmpty => t.thread_name }
+    val old_thread_selection: Option[String] =
+      thread_selection() orElse thread_entries.headOption.map(_.thread_name)
 
     tree.clearSelection
     root.removeAllChildren
@@ -185,6 +184,9 @@
 
     tree.getModel.asInstanceOf[DefaultTreeModel].reload(root)
 
+    tree.expandRow(0)
+    for (i <- Range.inclusive(tree.getRowCount - 1, 1, -1)) tree.expandRow(i)
+
     old_thread_selection match {
       case Some(thread_name) if thread_entries.exists(t => t.thread_name == thread_name) =>
         val i =
@@ -193,7 +195,6 @@
         tree.addSelectionRow(i + 1)
       case _ =>
     }
-    for (i <- 0 until tree.getRowCount) tree.expandRow(i)
 
     tree.revalidate()
   }