diff --git a/Makefile.am b/Makefile.am
index 2b64892..3c33728 100644
--- a/Makefile.am
+++ b/Makefile.am
@@ -302,6 +302,7 @@ sgpemv2_SOURCES = \
 	src/configure_policy_dialog.cc \
 	src/graphical_preferences_editor.cc \
 	src/gui_builder.cc \
+	src/holt_widget.cc \
 	src/main.cc \
 	src/parse_opts.cc \
 	src/resources_widget.cc \
@@ -318,6 +319,7 @@ noinst_HEADERS += \
 	src/configure_policy_dialog.hh \
 	src/graphical_preferences_editor.hh \
 	src/gui_builder.hh \
+	src/holt_widget.hh \
 	src/main.hh \
 	src/parse_opts.hh \
 	src/resources_widget.hh \
diff --git a/src/gui_builder.cc b/src/gui_builder.cc
index baf8b7d..9ad00c2 100644
--- a/src/gui_builder.cc
+++ b/src/gui_builder.cc
@@ -25,6 +25,7 @@
 
 #include "configure_policy_dialog.hh"
 #include "graphical_preferences_editor.hh"
+#include "holt_widget.hh"
 #include "schedulables_tree_widget.hh"
 #include "simulation_widget.hh"
 #include "resources_widget.hh"
@@ -517,7 +518,6 @@ GuiBuilder::GuiBuilder(const std::string& gladefile)
   // we have to remember to manually show custom added widgets:
   scheds_tree->show();
 
-
   // Resources ListView widget
   ResourcesWidget* resources_widget = NULL;
   _refXml->get_widget_derived("Resources.Tree", resources_widget);
@@ -527,9 +527,14 @@ GuiBuilder::GuiBuilder(const std::string& gladefile)
   // Main simulation widget  
   ScrolledWindow* simulation_window = NULL;
   _refXml->get_widget("SimulationScrolledWindow", simulation_window);
-  _simulation_widget = manage(new SimulationWidget(Simulation::get_instance()));
-  simulation_window->add(*_simulation_widget);
-  _simulation_widget->show();
+  SimulationWidget& simulation_widget = *manage(new SimulationWidget(Simulation::get_instance()));
+  simulation_window->add(simulation_widget);
+  simulation_widget.show();
+  
+  //  Why this works, and SimulationWidget doesn't ??
+  //  HoltWidget& holt = *manage(new HoltWidget(Simulation::get_instance()));
+  //   simulation_window->add(holt);
+  //   holt.show();
 }
 
 
diff --git a/src/gui_builder.hh b/src/gui_builder.hh
index 7450811..34ce26c 100644
--- a/src/gui_builder.hh
+++ b/src/gui_builder.hh
@@ -64,7 +64,6 @@ namespace sgpem
 
   private:
     Glib::RefPtr<Gnome::Glade::Xml> _refXml;
-    SimulationWidget*               _simulation_widget;
     SimulationController            _controller;
 
     // Used to store the loaded snapshot filename, when !empty
diff --git a/src/simulation_widget.cc b/src/simulation_widget.cc
index 4ba0227..3594a1c 100644
--- a/src/simulation_widget.cc
+++ b/src/simulation_widget.cc
@@ -585,6 +585,8 @@ SimulationWidget::draw_widget(cairo_t* ctx)
 void
 SimulationWidget::calc_drawing_size(cairo_t* ctx, size_t& width, size_t& height)
 {
+  std::cout << "Simulation widget BEFORE calc_drawing_size width=" << width << " height=" << height << std::endl;
+
   if(!_simulation)
     return;
   const History& hist = _simulation->get_history();
@@ -605,6 +607,8 @@ SimulationWidget::calc_drawing_size(cairo_t* ctx, size_t& width, size_t& height)
   height = (1.0 + 3.0 * _n_proc + 3.0) * _y_unit;
   if(_show_threads)
     height += _n_thr * _y_unit;
+
+  std::cout << "Simulation widget AFTER calc_drawing_size width=" << width << " height=" << height << std::endl;
 }
 
 void