src/Tools/jEdit/src/debugger_dockable.scala

   tree_pane.verticalScrollBarPolicy = ScrollPane.BarPolicy.Always
   tree_pane.minimumSize = new Dimension(200, 100)
 
 
   /* controls */
+
+  private val break_button = new CheckBox("Break") {
+    tooltip = "Break running threads at next possible breakpoint"
+    selected = Debugger.is_break()
+    reactions += { case ButtonClicked(_) => Debugger.set_break(selected) }
+  }
 
   private val continue_button = new Button("Continue") {
     tooltip = "Continue program on current thread, until next breakpoint"
     reactions += { case ButtonClicked(_) => thread_selection().map(Debugger.continue(_)) }
   }

 
   private val zoom = new Font_Info.Zoom_Box { def changed = handle_resize() }
 
   private val controls =
     new Wrap_Panel(Wrap_Panel.Alignment.Right)(
-      continue_button, step_button, step_over_button, step_out_button,
+      break_button, continue_button, step_button, step_over_button, step_out_button,
       context_label, Component.wrap(context_field),
       expression_label, Component.wrap(expression_field), eval_button, sml_button,
       pretty_text_area.search_label, pretty_text_area.search_field, zoom)
   add(controls.peer, BorderLayout.NORTH)
 

     Session.Consumer[Any](getClass.getName) {
       case _: Session.Global_Options =>
         GUI_Thread.later { handle_resize() }
 
       case Debugger.Update =>
-        GUI_Thread.later { handle_update() }
+        GUI_Thread.later {
+          break_button.selected = Debugger.is_break()
+          handle_update()
+        }
     }
 
   override def init()
   {
     PIDE.session.global_options += main