diff --git a/apps/calculation/history_controller.cpp b/apps/calculation/history_controller.cpp
index 8b9c0a453..ff8025660 100644
--- a/apps/calculation/history_controller.cpp
+++ b/apps/calculation/history_controller.cpp
@@ -127,7 +127,7 @@ void HistoryController::tableViewDidChangeSelection(SelectableTableView * t, int
   Container::activeApp()->setFirstResponder(selectedCell);
 }
 
-int HistoryController::numberOfRows() {
+int HistoryController::numberOfRows() const {
   return m_calculationStore->numberOfCalculations();
 };
 
diff --git a/apps/calculation/history_controller.h b/apps/calculation/history_controller.h
index 07e62a603..f4d1d61fb 100644
--- a/apps/calculation/history_controller.h
+++ b/apps/calculation/history_controller.h
@@ -18,7 +18,7 @@ public:
   void didBecomeFirstResponder() override;
   void willExitResponderChain(Responder * nextFirstResponder) override;
   void reload();
-  int numberOfRows() override;
+  int numberOfRows() const override;
   HighlightCell * reusableCell(int index, int type) override;
   int reusableCellCount(int type) override;
   void willDisplayCellForIndex(HighlightCell * cell, int index) override;
diff --git a/apps/code/console_controller.cpp b/apps/code/console_controller.cpp
index ce6bd2677..0a1c41586 100644
--- a/apps/code/console_controller.cpp
+++ b/apps/code/console_controller.cpp
@@ -196,7 +196,7 @@ bool ConsoleController::handleEvent(Ion::Events::Event event) {
   return false;
 }
 
-int ConsoleController::numberOfRows() {
+int ConsoleController::numberOfRows() const {
   return m_consoleStore.numberOfLines()+1;
 }
 
diff --git a/apps/code/console_controller.h b/apps/code/console_controller.h
index 43779f340..1c32f4f04 100644
--- a/apps/code/console_controller.h
+++ b/apps/code/console_controller.h
@@ -42,7 +42,7 @@ public:
   ViewController::DisplayParameter displayParameter() override { return ViewController::DisplayParameter::WantsMaximumSpace; }
 
   // ListViewDataSource
-  int numberOfRows() override;
+  int numberOfRows() const override;
   KDCoordinate rowHeight(int j) override;
   KDCoordinate cumulatedHeightFromIndex(int j) override;
   int indexFromCumulatedHeight(KDCoordinate offsetY) override;
diff --git a/apps/code/menu_controller.cpp b/apps/code/menu_controller.cpp
index 44288ae36..bed2c31cc 100644
--- a/apps/code/menu_controller.cpp
+++ b/apps/code/menu_controller.cpp
@@ -156,7 +156,7 @@ void MenuController::scriptContentEditionDidFinish() {
   reloadConsole();
 }
 
-int MenuController::numberOfRows() {
+int MenuController::numberOfRows() const {
   return m_scriptStore->numberOfScripts() + m_shouldDisplayAddScriptRow;
 }
 
diff --git a/apps/code/menu_controller.h b/apps/code/menu_controller.h
index 5848a302a..252b2f030 100644
--- a/apps/code/menu_controller.h
+++ b/apps/code/menu_controller.h
@@ -31,8 +31,8 @@ public:
   void viewWillAppear() override;
 
   /* TableViewDataSource */
-  int numberOfRows() override;
-  int numberOfColumns() override { return 2; }
+  int numberOfRows() const override;
+  int numberOfColumns() const override { return 2; }
   void willDisplayCellAtLocation(HighlightCell * cell, int i, int j) override;
   KDCoordinate columnWidth(int i) override;
   KDCoordinate rowHeight(int j) override { return Metric::StoreRowHeight; }
diff --git a/apps/code/python_toolbox.cpp b/apps/code/python_toolbox.cpp
index 6fa965ac4..55989b01d 100644
--- a/apps/code/python_toolbox.cpp
+++ b/apps/code/python_toolbox.cpp
@@ -374,7 +374,7 @@ bool PythonToolbox::selectLeaf(int selectedRow) {
   return true;
 }
 
-const ToolboxMessageTree * PythonToolbox::rootModel() {
+const ToolboxMessageTree * PythonToolbox::rootModel() const {
   return &toolboxModel;
 }
 
diff --git a/apps/code/python_toolbox.h b/apps/code/python_toolbox.h
index 939b86f78..0889f2ebf 100644
--- a/apps/code/python_toolbox.h
+++ b/apps/code/python_toolbox.h
@@ -15,7 +15,7 @@ public:
 protected:
   KDCoordinate rowHeight(int j) override;
   bool selectLeaf(int selectedRow) override;
-  const ToolboxMessageTree * rootModel() override;
+  const ToolboxMessageTree * rootModel() const override;
   MessageTableCellWithMessage * leafCellAtIndex(int index) override;
   MessageTableCellWithChevron* nodeCellAtIndex(int index) override;
   int maxNumberOfDisplayedRows() override;
diff --git a/apps/code/script_parameter_controller.h b/apps/code/script_parameter_controller.h
index 1fef1d752..c851922d9 100644
--- a/apps/code/script_parameter_controller.h
+++ b/apps/code/script_parameter_controller.h
@@ -25,8 +25,8 @@ public:
   /* SimpleListViewDataSource */
   KDCoordinate cellHeight() override { return Metric::ParameterCellHeight; }
   HighlightCell * reusableCell(int index) override;
-  int reusableCellCount() override { return k_totalNumberOfCell; }
-  int numberOfRows() override { return k_totalNumberOfCell; }
+  int reusableCellCount() const override { return k_totalNumberOfCell; }
+  int numberOfRows() const override { return k_totalNumberOfCell; }
   void willDisplayCellForIndex(HighlightCell * cell, int index) override;
 
 private:
diff --git a/apps/code/variable_box_controller.cpp b/apps/code/variable_box_controller.cpp
index 964656dfc..c937b4896 100644
--- a/apps/code/variable_box_controller.cpp
+++ b/apps/code/variable_box_controller.cpp
@@ -47,7 +47,7 @@ static bool shouldAddObject(const char * name, int maxLength) {
   return true;
 }
 
-int VariableBoxController::numberOfRows() {
+int VariableBoxController::numberOfRows() const {
   assert(m_scriptNodesCount <= k_maxScriptNodesCount);
   return m_scriptNodesCount;
 }
diff --git a/apps/code/variable_box_controller.h b/apps/code/variable_box_controller.h
index 6e1047126..79d107f00 100644
--- a/apps/code/variable_box_controller.h
+++ b/apps/code/variable_box_controller.h
@@ -17,7 +17,7 @@ public:
   void didEnterResponderChain(Responder * previousFirstResponder) override;
 
   /* ListViewDataSource */
-  int numberOfRows() override;
+  int numberOfRows() const override;
   int reusableCellCount(int type) override;
   void willDisplayCellForIndex(HighlightCell * cell, int index) override;
   int typeAtLocation(int i, int j) override;
diff --git a/apps/graph/graph/calculation_parameter_controller.cpp b/apps/graph/graph/calculation_parameter_controller.cpp
index c9594aa9b..b2ffbeb59 100644
--- a/apps/graph/graph/calculation_parameter_controller.cpp
+++ b/apps/graph/graph/calculation_parameter_controller.cpp
@@ -73,7 +73,7 @@ bool CalculationParameterController::handleEvent(Ion::Events::Event event) {
   return false;
 }
 
-int CalculationParameterController::numberOfRows() {
+int CalculationParameterController::numberOfRows() const {
   // Inverse row + [optional intersection row] + all other rows (max, min zeros, tangent, integral)
   return 1 + shouldDisplayIntersection() + k_totalNumberOfReusableCells - 1;
 };
diff --git a/apps/graph/graph/calculation_parameter_controller.h b/apps/graph/graph/calculation_parameter_controller.h
index 4c454faff..8318f7b14 100644
--- a/apps/graph/graph/calculation_parameter_controller.h
+++ b/apps/graph/graph/calculation_parameter_controller.h
@@ -23,7 +23,7 @@ public:
   bool handleEvent(Ion::Events::Event event) override;
   void viewWillAppear() override;
   void didBecomeFirstResponder() override;
-  int numberOfRows() override;
+  int numberOfRows() const override;
   KDCoordinate rowHeight(int j) override;
   HighlightCell * reusableCell(int index, int type) override;
   int reusableCellCount(int type) override;
diff --git a/apps/graph/graph/curve_parameter_controller.cpp b/apps/graph/graph/curve_parameter_controller.cpp
index 99f644119..15e0fb6e6 100644
--- a/apps/graph/graph/curve_parameter_controller.cpp
+++ b/apps/graph/graph/curve_parameter_controller.cpp
@@ -62,7 +62,7 @@ bool CurveParameterController::handleEvent(Ion::Events::Event event) {
   return false;
 }
 
-int CurveParameterController::numberOfRows() {
+int CurveParameterController::numberOfRows() const {
   return reusableCellCount();
 };
 
@@ -72,7 +72,7 @@ HighlightCell * CurveParameterController::reusableCell(int index) {
   return cells[cellIndex(index)];
 }
 
-int CurveParameterController::reusableCellCount() {
+int CurveParameterController::reusableCellCount() const {
   return 1 + (shouldDisplayCalculationAndDerivative() ? 2 : 0);
 }
 
diff --git a/apps/graph/graph/curve_parameter_controller.h b/apps/graph/graph/curve_parameter_controller.h
index f3bd82980..d5a587af1 100644
--- a/apps/graph/graph/curve_parameter_controller.h
+++ b/apps/graph/graph/curve_parameter_controller.h
@@ -14,9 +14,9 @@ public:
   CurveParameterController(InputEventHandlerDelegate * inputEventHandlerDelegate, Shared::InteractiveCurveViewRange * graphRange, BannerView * bannerView, Shared::CurveViewCursor * cursor, GraphView * graphView, GraphController * graphController);
   const char * title() override;
   bool handleEvent(Ion::Events::Event event) override;
-  int numberOfRows() override;
+  int numberOfRows() const override;
   HighlightCell * reusableCell(int index) override;
-  int reusableCellCount() override;
+  int reusableCellCount() const override;
   void willDisplayCellForIndex(HighlightCell * cell, int index) override;
   void viewWillAppear() override;
 private:
diff --git a/apps/graph/list/domain_parameter_controller.cpp b/apps/graph/list/domain_parameter_controller.cpp
index 26853b4ea..ad2d945e7 100644
--- a/apps/graph/list/domain_parameter_controller.cpp
+++ b/apps/graph/list/domain_parameter_controller.cpp
@@ -22,7 +22,7 @@ const char * DomainParameterController::title() {
   return I18n::translate(I18n::Message::FunctionDomain);
 }
 
-int DomainParameterController::numberOfRows() {
+int DomainParameterController::numberOfRows() const {
   return k_totalNumberOfCell+1;
 }
 
diff --git a/apps/graph/list/domain_parameter_controller.h b/apps/graph/list/domain_parameter_controller.h
index 738afd3c8..d0922d7c2 100644
--- a/apps/graph/list/domain_parameter_controller.h
+++ b/apps/graph/list/domain_parameter_controller.h
@@ -17,7 +17,7 @@ public:
   const char * title() override;
 
   // ListViewDataSource
-  int numberOfRows() override;
+  int numberOfRows() const override;
   void willDisplayCellForIndex(HighlightCell * cell, int index) override;
 
   void setRecord(Ion::Storage::Record record) { m_record = record; }
diff --git a/apps/graph/list/type_parameter_controller.h b/apps/graph/list/type_parameter_controller.h
index fbcc06867..be157a1a9 100644
--- a/apps/graph/list/type_parameter_controller.h
+++ b/apps/graph/list/type_parameter_controller.h
@@ -23,7 +23,7 @@ public:
   void viewWillAppear() override;
 
   // ListViewDataSource
-  int numberOfRows() override { return k_numberOfTypes; }
+  int numberOfRows() const override { return k_numberOfTypes; }
   KDCoordinate rowHeight(int j) override;
   void willDisplayCellForIndex(HighlightCell * cell, int index) override;
   MessageTableCellWithExpression * reusableCell(int index, int type) override;
diff --git a/apps/graph/values/derivative_parameter_controller.cpp b/apps/graph/values/derivative_parameter_controller.cpp
index 22f53e803..6ec2516ee 100644
--- a/apps/graph/values/derivative_parameter_controller.cpp
+++ b/apps/graph/values/derivative_parameter_controller.cpp
@@ -58,7 +58,7 @@ bool DerivativeParameterController::handleEvent(Ion::Events::Event event) {
   return false;
 }
 
-int DerivativeParameterController::numberOfRows() {
+int DerivativeParameterController::numberOfRows() const {
   return k_totalNumberOfCell;
 };
 
@@ -73,7 +73,7 @@ HighlightCell * DerivativeParameterController::reusableCell(int index) {
   return cells[index];
 }
 
-int DerivativeParameterController::reusableCellCount() {
+int DerivativeParameterController::reusableCellCount() const {
   return k_totalNumberOfCell;
 }
 
diff --git a/apps/graph/values/derivative_parameter_controller.h b/apps/graph/values/derivative_parameter_controller.h
index bd643b334..0aed8df16 100644
--- a/apps/graph/values/derivative_parameter_controller.h
+++ b/apps/graph/values/derivative_parameter_controller.h
@@ -17,10 +17,10 @@ public:
   bool handleEvent(Ion::Events::Event event) override;
   void viewWillAppear() override;
   void didBecomeFirstResponder() override;
-  int numberOfRows() override;
+  int numberOfRows() const override;
   KDCoordinate cellHeight() override;
   HighlightCell * reusableCell(int index) override;
-  int reusableCellCount() override;
+  int reusableCellCount() const  override;
   void setRecord(Ion::Storage::Record record) {
     m_record = record;
   }
diff --git a/apps/graph/values/function_parameter_controller.cpp b/apps/graph/values/function_parameter_controller.cpp
index d98ae7920..ae7ae2db8 100644
--- a/apps/graph/values/function_parameter_controller.cpp
+++ b/apps/graph/values/function_parameter_controller.cpp
@@ -38,7 +38,7 @@ bool FunctionParameterController::handleEvent(Ion::Events::Event event) {
   return false;
 }
 
-int FunctionParameterController::numberOfRows() {
+int FunctionParameterController::numberOfRows() const {
   return k_totalNumberOfCell;
 };
 
@@ -53,7 +53,7 @@ HighlightCell * FunctionParameterController::reusableCell(int index) {
   return cells[index];
 }
 
-int FunctionParameterController::reusableCellCount() {
+int FunctionParameterController::reusableCellCount() const {
   return k_totalNumberOfCell;
 }
 
diff --git a/apps/graph/values/function_parameter_controller.h b/apps/graph/values/function_parameter_controller.h
index 01f80ce32..54964b683 100644
--- a/apps/graph/values/function_parameter_controller.h
+++ b/apps/graph/values/function_parameter_controller.h
@@ -13,9 +13,9 @@ class FunctionParameterController : public Shared::ValuesFunctionParameterContro
 public:
   FunctionParameterController(ValuesController * valuesController);
   bool handleEvent(Ion::Events::Event event) override;
-  int numberOfRows() override;
+  int numberOfRows() const override;
   HighlightCell * reusableCell(int index) override;
-  int reusableCellCount() override;
+  int reusableCellCount() const override;
   void willDisplayCellForIndex(HighlightCell * cell, int index) override;
   void viewWillAppear() override;
 private:
diff --git a/apps/graph/values/interval_parameter_selector_controller.cpp b/apps/graph/values/interval_parameter_selector_controller.cpp
index 6be6dc44a..84536bd5e 100644
--- a/apps/graph/values/interval_parameter_selector_controller.cpp
+++ b/apps/graph/values/interval_parameter_selector_controller.cpp
@@ -44,7 +44,7 @@ bool IntervalParameterSelectorController::handleEvent(Ion::Events::Event event)
   return false;
 }
 
-int IntervalParameterSelectorController::numberOfRows() {
+int IntervalParameterSelectorController::numberOfRows() const {
   int rowCount = 0;
   int plotTypeIndex = 0;
   Shared::CartesianFunction::PlotType plotType;
@@ -62,7 +62,7 @@ HighlightCell * IntervalParameterSelectorController::reusableCell(int index) {
   return m_intervalParameterCell + index;
 }
 
-int IntervalParameterSelectorController::reusableCellCount() {
+int IntervalParameterSelectorController::reusableCellCount() const {
   return Shared::CartesianFunction::k_numberOfPlotTypes;
 }
 
diff --git a/apps/graph/values/interval_parameter_selector_controller.h b/apps/graph/values/interval_parameter_selector_controller.h
index 77ddbefd9..55a0b6543 100644
--- a/apps/graph/values/interval_parameter_selector_controller.h
+++ b/apps/graph/values/interval_parameter_selector_controller.h
@@ -15,9 +15,9 @@ public:
   void viewDidDisappear() override;
   bool handleEvent(Ion::Events::Event event) override;
   void didBecomeFirstResponder() override;
-  int numberOfRows() override;
+  int numberOfRows() const override;
   KDCoordinate cellHeight() override { return Metric::ParameterCellHeight; }
-  int reusableCellCount() override;
+  int reusableCellCount() const override;
   HighlightCell * reusableCell(int index) override;
   void willDisplayCellForIndex(HighlightCell * cell, int index) override;
   void setStartEndMessages(Shared::IntervalParameterController * controller, Shared::CartesianFunction::PlotType plotType);
diff --git a/apps/graph/values/values_controller.cpp b/apps/graph/values/values_controller.cpp
index 2e8488f83..5165d8d55 100644
--- a/apps/graph/values/values_controller.cpp
+++ b/apps/graph/values/values_controller.cpp
@@ -250,7 +250,7 @@ void ValuesController::setStartEndMessages(Shared::IntervalParameterController *
   m_intervalParameterSelectorController.setStartEndMessages(controller, plotTypeAtColumn(&c));
 }
 
-void ValuesController::updateNumberOfColumns() {
+void ValuesController::updateNumberOfColumns() const {
   for (int plotTypeIndex = 0; plotTypeIndex <  CartesianFunction::k_numberOfPlotTypes; plotTypeIndex++) {
     m_numberOfColumnsForType[plotTypeIndex] = 0;
   }
diff --git a/apps/graph/values/values_controller.h b/apps/graph/values/values_controller.h
index a2163f107..4f34ee37e 100644
--- a/apps/graph/values/values_controller.h
+++ b/apps/graph/values/values_controller.h
@@ -36,7 +36,7 @@ private:
   constexpr static int k_maxNumberOfCells = k_maxNumberOfFunctions * k_maxNumberOfRows;
 
   void setStartEndMessages(Shared::IntervalParameterController * controller, int column) override;
-  void updateNumberOfColumns() override;
+  void updateNumberOfColumns() const override;
   Ion::Storage::Record recordAtColumn(int i) override;
   Ion::Storage::Record recordAtColumn(int i, bool * isDerivative);
   int numberOfColumnsForRecord(Ion::Storage::Record record) const;
@@ -55,7 +55,7 @@ private:
   EvenOddMessageTextCell * abscissaTitleCells(int j) override { assert (j >= 0 && j < abscissaTitleCellsCount()); return &m_abscissaTitleCells[j]; }
   ViewController * functionParameterController() override;
 
-  int m_numberOfColumnsForType[Shared::CartesianFunction::k_numberOfPlotTypes];
+  mutable int m_numberOfColumnsForType[Shared::CartesianFunction::k_numberOfPlotTypes];
   Shared::BufferFunctionTitleCell m_functionTitleCells[k_maxNumberOfFunctions];
   Shared::HideableEvenOddBufferTextCell m_floatCells[k_maxNumberOfCells];
   AbscissaTitleCell m_abscissaTitleCells[Shared::CartesianFunction::k_numberOfPlotTypes];
diff --git a/apps/home/controller.cpp b/apps/home/controller.cpp
index 171197381..c59612d7a 100644
--- a/apps/home/controller.cpp
+++ b/apps/home/controller.cpp
@@ -91,11 +91,11 @@ View * Controller::view() {
   return &m_view;
 }
 
-int Controller::numberOfRows() {
+int Controller::numberOfRows() const {
   return ((numberOfIcons()-1)/k_numberOfColumns)+1;
 }
 
-int Controller::numberOfColumns() {
+int Controller::numberOfColumns() const {
   return k_numberOfColumns;
 }
 
@@ -111,7 +111,7 @@ HighlightCell * Controller::reusableCell(int index) {
   return &m_cells[index];
 }
 
-int Controller::reusableCellCount() {
+int Controller::reusableCellCount() const {
   return k_maxNumberOfCells;
 }
 
@@ -128,7 +128,7 @@ void Controller::willDisplayCellAtLocation(HighlightCell * cell, int i, int j) {
   }
 }
 
-int Controller::numberOfIcons() {
+int Controller::numberOfIcons() const {
   AppsContainer * container = AppsContainer::sharedAppsContainer();
   assert(container->numberOfApps() > 0);
   return container->numberOfApps() - 1;
diff --git a/apps/home/controller.h b/apps/home/controller.h
index 7750f1cb1..4c354bfb5 100644
--- a/apps/home/controller.h
+++ b/apps/home/controller.h
@@ -16,16 +16,16 @@ public:
   void didBecomeFirstResponder() override;
   void viewWillAppear() override;
 
-  virtual int numberOfRows() override;
-  virtual int numberOfColumns() override;
+  virtual int numberOfRows() const override;
+  virtual int numberOfColumns() const override;
   virtual KDCoordinate cellHeight() override;
   virtual KDCoordinate cellWidth() override;
   virtual HighlightCell * reusableCell(int index) override;
-  virtual int reusableCellCount() override;
+  virtual int reusableCellCount() const override;
   void willDisplayCellAtLocation(HighlightCell * cell, int i, int j) override;
   void tableViewDidChangeSelection(SelectableTableView * t, int previousSelectedCellX, int previousSelectedCellY, bool withinTemporarySelection) override;
 private:
-  int numberOfIcons();
+  int numberOfIcons() const;
   SelectableTableViewDataSource * selectionDataSource() const;
   class ContentView : public View {
   public:
diff --git a/apps/math_toolbox.cpp b/apps/math_toolbox.cpp
index 929e66529..a91234b96 100644
--- a/apps/math_toolbox.cpp
+++ b/apps/math_toolbox.cpp
@@ -138,7 +138,7 @@ bool MathToolbox::selectLeaf(int selectedRow) {
   return true;
 }
 
-const ToolboxMessageTree * MathToolbox::rootModel() {
+const ToolboxMessageTree * MathToolbox::rootModel() const {
   return &toolboxModel;
 }
 
diff --git a/apps/math_toolbox.h b/apps/math_toolbox.h
index 3577edd04..77bc6bd56 100644
--- a/apps/math_toolbox.h
+++ b/apps/math_toolbox.h
@@ -9,7 +9,7 @@ public:
   MathToolbox();
 protected:
   bool selectLeaf(int selectedRow) override;
-  const ToolboxMessageTree * rootModel() override;
+  const ToolboxMessageTree * rootModel() const override;
   MessageTableCellWithMessage * leafCellAtIndex(int index) override;
   MessageTableCellWithChevron* nodeCellAtIndex(int index) override;
   int maxNumberOfDisplayedRows() override;
diff --git a/apps/probability/calculation_controller.cpp b/apps/probability/calculation_controller.cpp
index a4e732775..a455c4692 100644
--- a/apps/probability/calculation_controller.cpp
+++ b/apps/probability/calculation_controller.cpp
@@ -105,11 +105,11 @@ void CalculationController::viewDidDisappear() {
   ViewController::viewDidDisappear();
 }
 
-int CalculationController::numberOfRows() {
+int CalculationController::numberOfRows() const {
   return 1;
 }
 
-int CalculationController::numberOfColumns() {
+int CalculationController::numberOfColumns() const {
   return m_calculation->numberOfParameters()+1;
 }
 
diff --git a/apps/probability/calculation_controller.h b/apps/probability/calculation_controller.h
index e785b7321..4c49dd9a0 100644
--- a/apps/probability/calculation_controller.h
+++ b/apps/probability/calculation_controller.h
@@ -25,8 +25,8 @@ public:
   void viewDidDisappear() override;
 
   /* TableViewDataSource */
-  int numberOfRows() override;
-  int numberOfColumns() override;
+  int numberOfRows() const override;
+  int numberOfColumns() const override;
   KDCoordinate columnWidth(int i) override;
   KDCoordinate rowHeight(int j) override;
   KDCoordinate cumulatedHeightFromIndex(int j) override;
diff --git a/apps/probability/calculation_type_controller.cpp b/apps/probability/calculation_type_controller.cpp
index 6e3504d0b..036589437 100644
--- a/apps/probability/calculation_type_controller.cpp
+++ b/apps/probability/calculation_type_controller.cpp
@@ -59,7 +59,7 @@ bool CalculationTypeController::handleEvent(Ion::Events::Event event) {
   return false;
 }
 
-int CalculationTypeController::numberOfRows() {
+int CalculationTypeController::numberOfRows() const {
   if (m_distribution->isContinuous()) {
     return k_numberOfImages-1;
   }
@@ -80,7 +80,7 @@ HighlightCell * CalculationTypeController::reusableCell(int index) {
   return &m_imageCells[index];
 }
 
-int CalculationTypeController::reusableCellCount() {
+int CalculationTypeController::reusableCellCount() const {
   return k_numberOfImages;
 }
 
diff --git a/apps/probability/calculation_type_controller.h b/apps/probability/calculation_type_controller.h
index 94f655120..e850322e2 100644
--- a/apps/probability/calculation_type_controller.h
+++ b/apps/probability/calculation_type_controller.h
@@ -18,11 +18,11 @@ public:
   void viewDidDisappear() override;
   void didBecomeFirstResponder() override;
   bool handleEvent(Ion::Events::Event event) override;
-  int numberOfRows() override;
+  int numberOfRows() const override;
   KDCoordinate cellWidth() override;
   KDCoordinate cellHeight() override;
   HighlightCell * reusableCell(int index) override;
-  int reusableCellCount() override;
+  int reusableCellCount() const override;
   void willDisplayCellForIndex(HighlightCell * cell, int index) override;
   constexpr static int k_numberOfImages = 4;
 private:
diff --git a/apps/probability/distribution_controller.cpp b/apps/probability/distribution_controller.cpp
index ba801c976..ec89a49ac 100644
--- a/apps/probability/distribution_controller.cpp
+++ b/apps/probability/distribution_controller.cpp
@@ -104,7 +104,7 @@ bool Probability::DistributionController::handleEvent(Ion::Events::Event event)
   return false;
 }
 
-int Probability::DistributionController::numberOfRows() {
+int Probability::DistributionController::numberOfRows() const {
   return k_totalNumberOfModels;
 };
 
@@ -114,7 +114,7 @@ HighlightCell * Probability::DistributionController::reusableCell(int index) {
   return &m_cells[index];
 }
 
-int Probability::DistributionController::reusableCellCount() {
+int Probability::DistributionController::reusableCellCount() const {
   return k_totalNumberOfModels;
 }
 
diff --git a/apps/probability/distribution_controller.h b/apps/probability/distribution_controller.h
index a75e3f5bb..d81fca8c7 100644
--- a/apps/probability/distribution_controller.h
+++ b/apps/probability/distribution_controller.h
@@ -16,11 +16,11 @@ public:
   bool handleEvent(Ion::Events::Event event) override;
   void didBecomeFirstResponder() override;
   void viewWillAppear() override;
-  int numberOfRows() override;
+  int numberOfRows() const override;
   void willDisplayCellForIndex(HighlightCell * cell, int index) override;
   KDCoordinate cellHeight() override;
   HighlightCell * reusableCell(int index) override;
-  int reusableCellCount() override;
+  int reusableCellCount() const override;
 private:
   class ContentView : public View {
   public:
diff --git a/apps/probability/parameters_controller.cpp b/apps/probability/parameters_controller.cpp
index 96d9dfbb2..3d655dd69 100644
--- a/apps/probability/parameters_controller.cpp
+++ b/apps/probability/parameters_controller.cpp
@@ -111,7 +111,7 @@ void ParametersController::viewWillAppear() {
   FloatParameterController::viewWillAppear();
 }
 
-int ParametersController::numberOfRows() {
+int ParametersController::numberOfRows() const {
   return 1+m_distribution->numberOfParameter();
 }
 
diff --git a/apps/probability/parameters_controller.h b/apps/probability/parameters_controller.h
index 833854cd9..390b3099d 100644
--- a/apps/probability/parameters_controller.h
+++ b/apps/probability/parameters_controller.h
@@ -17,7 +17,7 @@ public:
   void reinitCalculation();
   void didBecomeFirstResponder() override;
   void viewWillAppear() override;
-  int numberOfRows() override;
+  int numberOfRows() const override;
   void willDisplayCellForIndex(HighlightCell * cell, int index) override;
 private:
   HighlightCell * reusableParameterCell(int index, int type) override;
diff --git a/apps/regression/calculation_controller.cpp b/apps/regression/calculation_controller.cpp
index 8ba925910..f2c0da050 100644
--- a/apps/regression/calculation_controller.cpp
+++ b/apps/regression/calculation_controller.cpp
@@ -114,11 +114,11 @@ Responder * CalculationController::defaultController() {
   return tabController();
 }
 
-int CalculationController::numberOfRows() {
+int CalculationController::numberOfRows() const {
   return 1 + k_totalNumberOfDoubleBufferRows + 4 + maxNumberOfCoefficients() + hasLinearRegression() * 2;
 }
 
-int CalculationController::numberOfColumns() {
+int CalculationController::numberOfColumns() const {
   return 1 + m_store->numberOfNonEmptySeries();
 }
 
diff --git a/apps/regression/calculation_controller.h b/apps/regression/calculation_controller.h
index 35881290d..a9ecc1fe8 100644
--- a/apps/regression/calculation_controller.h
+++ b/apps/regression/calculation_controller.h
@@ -37,8 +37,8 @@ public:
   Responder * defaultController() override;
 
   // TableViewDataSource
-  int numberOfRows() override;
-  int numberOfColumns() override;
+  int numberOfRows() const override;
+  int numberOfColumns() const override;
   void willDisplayCellAtLocation(HighlightCell * cell, int i, int j) override;
   KDCoordinate columnWidth(int i) override;
   KDCoordinate rowHeight(int j) override;
diff --git a/apps/regression/graph_options_controller.cpp b/apps/regression/graph_options_controller.cpp
index de03068a1..83d80db43 100644
--- a/apps/regression/graph_options_controller.cpp
+++ b/apps/regression/graph_options_controller.cpp
@@ -54,7 +54,7 @@ bool GraphOptionsController::handleEvent(Ion::Events::Event event) {
   return false;
 }
 
-int GraphOptionsController::numberOfRows() {
+int GraphOptionsController::numberOfRows() const {
   return k_numberOfParameterCells + 1;
 }
 
diff --git a/apps/regression/graph_options_controller.h b/apps/regression/graph_options_controller.h
index 796ca795a..69ec697bf 100644
--- a/apps/regression/graph_options_controller.h
+++ b/apps/regression/graph_options_controller.h
@@ -20,7 +20,7 @@ public:
   void viewWillAppear() override;
 
   //ListViewDataSource
-  int numberOfRows() override;
+  int numberOfRows() const override;
   KDCoordinate rowHeight(int j) override;
   KDCoordinate cumulatedHeightFromIndex(int j) override;
   int indexFromCumulatedHeight(KDCoordinate offsetY) override;
diff --git a/apps/regression/initialisation_parameter_controller.cpp b/apps/regression/initialisation_parameter_controller.cpp
index 76600ce88..421d3f7c3 100644
--- a/apps/regression/initialisation_parameter_controller.cpp
+++ b/apps/regression/initialisation_parameter_controller.cpp
@@ -37,7 +37,7 @@ bool InitialisationParameterController::handleEvent(Ion::Events::Event event) {
   return false;
 }
 
-int InitialisationParameterController::numberOfRows() {
+int InitialisationParameterController::numberOfRows() const {
   return k_totalNumberOfCells;
 };
 
@@ -48,7 +48,7 @@ HighlightCell * InitialisationParameterController::reusableCell(int index) {
   return &m_cells[index];
 }
 
-int InitialisationParameterController::reusableCellCount() {
+int InitialisationParameterController::reusableCellCount() const {
   return k_totalNumberOfCells;
 }
 
diff --git a/apps/regression/initialisation_parameter_controller.h b/apps/regression/initialisation_parameter_controller.h
index 19ba8b26a..d3c97b59e 100644
--- a/apps/regression/initialisation_parameter_controller.h
+++ b/apps/regression/initialisation_parameter_controller.h
@@ -14,10 +14,10 @@ public:
   const char * title() override;
   bool handleEvent(Ion::Events::Event event) override;
   void didBecomeFirstResponder() override;
-  int numberOfRows() override;
+  int numberOfRows() const override;
   KDCoordinate cellHeight() override;
   HighlightCell * reusableCell(int index) override;
-  int reusableCellCount() override;
+  int reusableCellCount() const override;
   void willDisplayCellForIndex(HighlightCell * cell, int index) override;
 private:
   constexpr static int k_totalNumberOfCells = 3;
diff --git a/apps/regression/regression_controller.h b/apps/regression/regression_controller.h
index 19c462fa3..a843908a4 100644
--- a/apps/regression/regression_controller.h
+++ b/apps/regression/regression_controller.h
@@ -27,7 +27,7 @@ public:
   HighlightCell * reusableCell(int index, int type) override;
   int reusableCellCount(int type) override { return k_numberOfCells; }
   int typeAtLocation(int i, int j) override { return 0; }
-  int numberOfRows() override { return k_numberOfRows; }
+  int numberOfRows() const override { return k_numberOfRows; }
   void willDisplayCellAtLocation(HighlightCell * cell, int i, int j) override;
 private:
   constexpr static int k_numberOfRows = 9;
diff --git a/apps/regression/store_parameter_controller.h b/apps/regression/store_parameter_controller.h
index 48b81fdcc..08c532405 100644
--- a/apps/regression/store_parameter_controller.h
+++ b/apps/regression/store_parameter_controller.h
@@ -16,7 +16,7 @@ public:
   void viewWillAppear() override;
   void didBecomeFirstResponder() override;
   // ListViewDataSource
-  int numberOfRows() override { return Shared::StoreParameterController::numberOfRows() + 1; }
+  int numberOfRows() const override { return Shared::StoreParameterController::numberOfRows() + 1; }
   KDCoordinate rowHeight(int j) override;
   HighlightCell * reusableCell(int index, int type) override;
   int reusableCellCount(int type) override;
diff --git a/apps/sequence/graph/curve_parameter_controller.cpp b/apps/sequence/graph/curve_parameter_controller.cpp
index 2497a6cbc..cab2f4330 100644
--- a/apps/sequence/graph/curve_parameter_controller.cpp
+++ b/apps/sequence/graph/curve_parameter_controller.cpp
@@ -37,7 +37,7 @@ bool CurveParameterController::handleEvent(Ion::Events::Event event) {
   return false;
 }
 
-int CurveParameterController::numberOfRows() {
+int CurveParameterController::numberOfRows() const {
   return k_totalNumberOfCells;
 };
 
@@ -48,7 +48,7 @@ HighlightCell * CurveParameterController::reusableCell(int index) {
   return cells[index];
 }
 
-int CurveParameterController::reusableCellCount() {
+int CurveParameterController::reusableCellCount() const {
   return k_totalNumberOfCells;
 }
 
diff --git a/apps/sequence/graph/curve_parameter_controller.h b/apps/sequence/graph/curve_parameter_controller.h
index b2919ec9b..7d47f1f6d 100644
--- a/apps/sequence/graph/curve_parameter_controller.h
+++ b/apps/sequence/graph/curve_parameter_controller.h
@@ -13,9 +13,9 @@ public:
   CurveParameterController(InputEventHandlerDelegate * inputEventHandlerDelegate, GraphController * graphController, Shared::InteractiveCurveViewRange * graphRange, Shared::CurveViewCursor * cursor);
   const char * title() override;
   bool handleEvent(Ion::Events::Event event) override;
-  int numberOfRows() override;
+  int numberOfRows() const override;
   HighlightCell * reusableCell(int index) override;
-  int reusableCellCount() override;
+  int reusableCellCount() const override;
 private:
   constexpr static int k_totalNumberOfCells = 2;
   GoToParameterController * goToParameterController() override;
diff --git a/apps/sequence/list/list_controller.cpp b/apps/sequence/list/list_controller.cpp
index 511abaf84..e3e2f631c 100644
--- a/apps/sequence/list/list_controller.cpp
+++ b/apps/sequence/list/list_controller.cpp
@@ -27,16 +27,15 @@ const char * ListController::title() {
   return I18n::translate(I18n::Message::SequenceTab);
 }
 
-int ListController::numberOfExpressionRows() {
+int ListController::numberOfExpressionRows() const {
   int numberOfRows = 0;
-  for (int i = 0; i < modelStore()->numberOfModels(); i++) {
-    Sequence * sequence = modelStore()->modelForRecord(modelStore()->recordAtIndex(i));
+  SequenceStore * store = const_cast<ListController *>(this)->modelStore();
+  const int modelsCount = store->numberOfModels();
+  for (int i = 0; i < modelsCount; i++) {
+    Sequence * sequence = store->modelForRecord(store->recordAtIndex(i));
     numberOfRows += sequence->numberOfElements();
   }
-  if (modelStore()->numberOfModels() == modelStore()->maxNumberOfModels()) {
-    return numberOfRows;
-  }
-  return 1 + numberOfRows;
+  return numberOfRows + (modelsCount == store->maxNumberOfModels()? 0 : 1);
 };
 
 KDCoordinate ListController::expressionRowHeight(int j) {
diff --git a/apps/sequence/list/list_controller.h b/apps/sequence/list/list_controller.h
index 85f942d20..c5d7d5e1a 100644
--- a/apps/sequence/list/list_controller.h
+++ b/apps/sequence/list/list_controller.h
@@ -19,7 +19,7 @@ class ListController : public Shared::FunctionListController, public Shared::Inp
 public:
   ListController(Responder * parentResponder, ::InputEventHandlerDelegate * inputEventHandlerDelegate, ButtonRowController * header, ButtonRowController * footer);
   const char * title() override;
-  int numberOfExpressionRows() override;
+  int numberOfExpressionRows() const override;
   KDCoordinate expressionRowHeight(int j) override;
   void willDisplayCellAtLocation(HighlightCell * cell, int i, int j) override;
   Toolbox * toolboxForInputEventHandler(InputEventHandler * handler) override;
diff --git a/apps/sequence/list/sequence_toolbox.cpp b/apps/sequence/list/sequence_toolbox.cpp
index d7e11a8f0..9037a34c5 100644
--- a/apps/sequence/list/sequence_toolbox.cpp
+++ b/apps/sequence/list/sequence_toolbox.cpp
@@ -26,7 +26,7 @@ bool SequenceToolbox::handleEvent(Ion::Events::Event event) {
   return MathToolbox::handleEventForRow(event, mathToolboxIndex(selectedRow()));
 }
 
-int SequenceToolbox::numberOfRows() {
+int SequenceToolbox::numberOfRows() const {
   if (stackDepth() == 0) {
     return MathToolbox::numberOfRows()+m_numberOfAddedCells;
   }
diff --git a/apps/sequence/list/sequence_toolbox.h b/apps/sequence/list/sequence_toolbox.h
index fc4450e82..c67122a9f 100644
--- a/apps/sequence/list/sequence_toolbox.h
+++ b/apps/sequence/list/sequence_toolbox.h
@@ -11,7 +11,7 @@ class SequenceToolbox : public MathToolbox {
 public:
   SequenceToolbox();
   bool handleEvent(Ion::Events::Event event) override;
-  int numberOfRows() override;
+  int numberOfRows() const override;
   HighlightCell * reusableCell(int index, int type) override;
   void willDisplayCellForIndex(HighlightCell * cell, int index) override;
   int typeAtLocation(int i, int j) override;
diff --git a/apps/sequence/list/type_parameter_controller.cpp b/apps/sequence/list/type_parameter_controller.cpp
index 3f30a08b3..fca5f400d 100644
--- a/apps/sequence/list/type_parameter_controller.cpp
+++ b/apps/sequence/list/type_parameter_controller.cpp
@@ -92,7 +92,7 @@ bool TypeParameterController::handleEvent(Ion::Events::Event event) {
   return false;
 }
 
-int TypeParameterController::numberOfRows() {
+int TypeParameterController::numberOfRows() const {
   return k_totalNumberOfCell;
 };
 
@@ -103,7 +103,7 @@ HighlightCell * TypeParameterController::reusableCell(int index) {
   return cells[index];
 }
 
-int TypeParameterController::reusableCellCount() {
+int TypeParameterController::reusableCellCount() const {
   return k_totalNumberOfCell;
 }
 
diff --git a/apps/sequence/list/type_parameter_controller.h b/apps/sequence/list/type_parameter_controller.h
index 58a944399..711e0f073 100644
--- a/apps/sequence/list/type_parameter_controller.h
+++ b/apps/sequence/list/type_parameter_controller.h
@@ -20,10 +20,10 @@ public:
   void viewDidDisappear() override;
   void didBecomeFirstResponder() override;
   bool handleEvent(Ion::Events::Event event) override;
-  int numberOfRows() override;
+  int numberOfRows() const override;
   KDCoordinate cellHeight() override;
   HighlightCell * reusableCell(int index) override;
-  int reusableCellCount() override;
+  int reusableCellCount() const override;
   void willDisplayCellAtLocation(HighlightCell * cell, int i, int j) override;
   void setRecord(Ion::Storage::Record record);
 private:
diff --git a/apps/settings/main_controller.cpp b/apps/settings/main_controller.cpp
index 42c68fbfd..74ba5787c 100644
--- a/apps/settings/main_controller.cpp
+++ b/apps/settings/main_controller.cpp
@@ -85,7 +85,7 @@ bool MainController::handleEvent(Ion::Events::Event event) {
   return false;
 }
 
-int MainController::numberOfRows() {
+int MainController::numberOfRows() const {
   return model()->numberOfChildren();
 };
 
diff --git a/apps/settings/main_controller.h b/apps/settings/main_controller.h
index 7d9d68d71..32db50c66 100644
--- a/apps/settings/main_controller.h
+++ b/apps/settings/main_controller.h
@@ -17,7 +17,7 @@ public:
   View * view() override;
   bool handleEvent(Ion::Events::Event event) override;
   void didBecomeFirstResponder() override;
-  int numberOfRows() override;
+  int numberOfRows() const override;
   KDCoordinate rowHeight(int j) override;
   KDCoordinate cumulatedHeightFromIndex(int j) override;
   int indexFromCumulatedHeight(KDCoordinate offsetY) override;
diff --git a/apps/settings/sub_menu/generic_sub_controller.cpp b/apps/settings/sub_menu/generic_sub_controller.cpp
index f69895893..96c0a39a4 100644
--- a/apps/settings/sub_menu/generic_sub_controller.cpp
+++ b/apps/settings/sub_menu/generic_sub_controller.cpp
@@ -39,7 +39,7 @@ bool GenericSubController::handleEvent(Ion::Events::Event event) {
   return false;
 }
 
-int GenericSubController::numberOfRows() {
+int GenericSubController::numberOfRows() const {
   if (m_messageTreeModel) {
     return m_messageTreeModel->numberOfChildren();
   }
diff --git a/apps/settings/sub_menu/generic_sub_controller.h b/apps/settings/sub_menu/generic_sub_controller.h
index 1325de9a7..132cc1773 100644
--- a/apps/settings/sub_menu/generic_sub_controller.h
+++ b/apps/settings/sub_menu/generic_sub_controller.h
@@ -13,7 +13,7 @@ public:
   View * view() override;
   void didBecomeFirstResponder() override;
   bool handleEvent(Ion::Events::Event event) override;
-  int numberOfRows() override;
+  int numberOfRows() const override;
   KDCoordinate rowHeight(int j) override;
   KDCoordinate cumulatedHeightFromIndex(int j) override;
   int indexFromCumulatedHeight(KDCoordinate offsetY) override;
diff --git a/apps/shared/editable_cell_table_view_controller.cpp b/apps/shared/editable_cell_table_view_controller.cpp
index 77378f56b..b17b50f35 100644
--- a/apps/shared/editable_cell_table_view_controller.cpp
+++ b/apps/shared/editable_cell_table_view_controller.cpp
@@ -56,7 +56,7 @@ bool EditableCellTableViewController::textFieldDidFinishEditing(TextField * text
   return true;
 }
 
-int EditableCellTableViewController::numberOfRows() {
+int EditableCellTableViewController::numberOfRows() const {
   int numberOfModelElements = 0;
   for (int i = 0; i < numberOfColumns(); i++) {
     numberOfModelElements = maxInt(numberOfModelElements, numberOfElementsInColumn(i));
diff --git a/apps/shared/editable_cell_table_view_controller.h b/apps/shared/editable_cell_table_view_controller.h
index 567c80213..b196dff17 100644
--- a/apps/shared/editable_cell_table_view_controller.h
+++ b/apps/shared/editable_cell_table_view_controller.h
@@ -15,7 +15,7 @@ public:
   bool textFieldShouldFinishEditing(TextField * textField, Ion::Events::Event event) override;
   bool textFieldDidFinishEditing(TextField * textField, const char * text, Ion::Events::Event event) override;
 
-  int numberOfRows() override;
+  int numberOfRows() const override;
   void willDisplayCellAtLocationWithDisplayMode(HighlightCell * cell, int i, int j, Poincare::Preferences::PrintFloatMode mode);
   KDCoordinate rowHeight(int j) override;
   void viewWillAppear() override;
@@ -33,7 +33,7 @@ private:
   virtual bool cellAtLocationIsEditable(int columnIndex, int rowIndex) = 0;
   virtual bool setDataAtLocation(double floatBody, int columnIndex, int rowIndex) = 0;
   virtual double dataAtLocation(int columnIndex, int rowIndex) = 0;
-  virtual int numberOfElementsInColumn(int columnIndex) = 0;
+  virtual int numberOfElementsInColumn(int columnIndex) const = 0;
   virtual int maxNumberOfElements() const = 0;
 };
 
diff --git a/apps/shared/expression_model_list_controller.cpp b/apps/shared/expression_model_list_controller.cpp
index 684afbf74..174381ef4 100644
--- a/apps/shared/expression_model_list_controller.cpp
+++ b/apps/shared/expression_model_list_controller.cpp
@@ -140,11 +140,10 @@ int ExpressionModelListController::memoizedIndexFromCumulatedHeight(KDCoordinate
   return notMemoizedIndexFromCumulatedHeight(offsetY);
 }
 
-int ExpressionModelListController::numberOfExpressionRows() {
-  if (modelStore()->numberOfModels() == modelStore()->maxNumberOfModels()) {
-    return modelStore()->numberOfModels();
-  }
-  return 1 + modelStore()->numberOfModels();
+int ExpressionModelListController::numberOfExpressionRows() const {
+  const ExpressionModelStore * store = const_cast<ExpressionModelListController *>(this)->modelStore();
+  int modelsCount = store->numberOfModels();
+  return modelsCount + (modelsCount == store->maxNumberOfModels() ? 0 : 1);
 }
 
 KDCoordinate ExpressionModelListController::expressionRowHeight(int j) {
diff --git a/apps/shared/expression_model_list_controller.h b/apps/shared/expression_model_list_controller.h
index be8e3c568..4dbd8a4b5 100644
--- a/apps/shared/expression_model_list_controller.h
+++ b/apps/shared/expression_model_list_controller.h
@@ -15,7 +15,7 @@ protected:
   // SelectableTableViewDelegate
   void tableViewDidChangeSelection(SelectableTableView * t, int previousSelectedCellX, int previousSelectedCellY, bool withinTemporarySelection) override;
   // TableViewDataSource
-  virtual int numberOfExpressionRows();
+  virtual int numberOfExpressionRows() const;
   KDCoordinate memoizedRowHeight(int j);
   KDCoordinate memoizedCumulatedHeightFromIndex(int j);
   int memoizedIndexFromCumulatedHeight(KDCoordinate offsetY);
diff --git a/apps/shared/function_list_controller.h b/apps/shared/function_list_controller.h
index 8bc0dd055..4499e4bea 100644
--- a/apps/shared/function_list_controller.h
+++ b/apps/shared/function_list_controller.h
@@ -18,11 +18,11 @@ public:
   void viewWillAppear() override;
 
   /* TableViewDataSource */
-  int numberOfRows() override { return this->numberOfExpressionRows(); }
+  int numberOfRows() const override { return this->numberOfExpressionRows(); }
   KDCoordinate rowHeight(int j) override { return ExpressionModelListController::memoizedRowHeight(j); }
   KDCoordinate cumulatedHeightFromIndex(int j) override { return ExpressionModelListController::memoizedCumulatedHeightFromIndex(j); }
   int indexFromCumulatedHeight(KDCoordinate offsetY) override { return ExpressionModelListController::memoizedIndexFromCumulatedHeight(offsetY); }
-  int numberOfColumns() override { return 2; }
+  int numberOfColumns() const override { return 2; }
   KDCoordinate columnWidth(int i) override;
   KDCoordinate cumulatedWidthFromIndex(int i) override;
   int indexFromCumulatedWidth(KDCoordinate offsetX) override;
diff --git a/apps/shared/go_to_parameter_controller.cpp b/apps/shared/go_to_parameter_controller.cpp
index 40bf3b48f..d72ab64d9 100644
--- a/apps/shared/go_to_parameter_controller.cpp
+++ b/apps/shared/go_to_parameter_controller.cpp
@@ -11,7 +11,7 @@ GoToParameterController::GoToParameterController(Responder * parentResponder, In
 {
 }
 
-int GoToParameterController::numberOfRows() {
+int GoToParameterController::numberOfRows() const {
   return 2;
 }
 
diff --git a/apps/shared/go_to_parameter_controller.h b/apps/shared/go_to_parameter_controller.h
index 8c19079b0..31516b923 100644
--- a/apps/shared/go_to_parameter_controller.h
+++ b/apps/shared/go_to_parameter_controller.h
@@ -11,7 +11,7 @@ namespace Shared {
 class GoToParameterController : public FloatParameterController<double> {
 public:
   GoToParameterController(Responder * parentResponder, InputEventHandlerDelegate * inputEventHandlerDelegate, InteractiveCurveViewRange * graphRange, CurveViewCursor * cursor);
-  int numberOfRows() override;
+  int numberOfRows() const override;
   bool handleEvent(Ion::Events::Event event) override;
 protected:
   void setParameterName(I18n::Message message) { m_parameterCell.setMessage(message); }
diff --git a/apps/shared/initialisation_parameter_controller.cpp b/apps/shared/initialisation_parameter_controller.cpp
index 6e8fa00ce..531fed091 100644
--- a/apps/shared/initialisation_parameter_controller.cpp
+++ b/apps/shared/initialisation_parameter_controller.cpp
@@ -32,7 +32,7 @@ void InitialisationParameterController::didBecomeFirstResponder() {
   Container::activeApp()->setFirstResponder(&m_selectableTableView);
 }
 
-int InitialisationParameterController::numberOfRows() {
+int InitialisationParameterController::numberOfRows() const {
   return k_totalNumberOfCells;
 }
 
@@ -46,7 +46,7 @@ HighlightCell * InitialisationParameterController::reusableCell(int index) {
   return &m_cells[index];
 }
 
-int InitialisationParameterController::reusableCellCount() {
+int InitialisationParameterController::reusableCellCount() const {
   return k_totalNumberOfCells;
 }
 
diff --git a/apps/shared/initialisation_parameter_controller.h b/apps/shared/initialisation_parameter_controller.h
index 83bb27adf..5a7e33186 100644
--- a/apps/shared/initialisation_parameter_controller.h
+++ b/apps/shared/initialisation_parameter_controller.h
@@ -18,10 +18,10 @@ public:
   const char * title() override;
   bool handleEvent(Ion::Events::Event event) override;
   void didBecomeFirstResponder() override;
-  int numberOfRows() override;
+  int numberOfRows() const override;
   KDCoordinate cellHeight() override;
   HighlightCell * reusableCell(int index) override;
-  int reusableCellCount() override;
+  int reusableCellCount() const override;
   void willDisplayCellForIndex(HighlightCell * cell, int index) override;
 private:
   constexpr static int k_totalNumberOfCells = 4;
diff --git a/apps/shared/interval_parameter_controller.cpp b/apps/shared/interval_parameter_controller.cpp
index ce1587f57..7ab9e275c 100644
--- a/apps/shared/interval_parameter_controller.cpp
+++ b/apps/shared/interval_parameter_controller.cpp
@@ -20,7 +20,7 @@ const char * IntervalParameterController::title() {
   return I18n::translate(m_title);
 }
 
-int IntervalParameterController::numberOfRows() {
+int IntervalParameterController::numberOfRows() const {
   return k_totalNumberOfCell+1;
 }
 
diff --git a/apps/shared/interval_parameter_controller.h b/apps/shared/interval_parameter_controller.h
index c0d01d7d9..9ed10d99b 100644
--- a/apps/shared/interval_parameter_controller.h
+++ b/apps/shared/interval_parameter_controller.h
@@ -16,7 +16,7 @@ public:
   const char * title() override;
   void setTitle(I18n::Message title) { m_title = title; }
   void willDisplayCellForIndex(HighlightCell * cell, int index) override;
-  int numberOfRows() override;
+  int numberOfRows() const override;
   void setStartEndMessages(I18n::Message startMessage, I18n::Message endMessage);
 protected:
   constexpr static int k_totalNumberOfCell = 3;
diff --git a/apps/shared/language_controller.cpp b/apps/shared/language_controller.cpp
index 68e047616..704e08562 100644
--- a/apps/shared/language_controller.cpp
+++ b/apps/shared/language_controller.cpp
@@ -49,7 +49,7 @@ bool LanguageController::handleEvent(Ion::Events::Event event) {
   return false;
 }
 
-int LanguageController::numberOfRows() {
+int LanguageController::numberOfRows() const {
   return I18n::NumberOfLanguages;
 }
 
@@ -61,7 +61,7 @@ HighlightCell * LanguageController::reusableCell(int index) {
   return &m_cells[index];
 }
 
-int LanguageController::reusableCellCount() {
+int LanguageController::reusableCellCount() const {
   return I18n::NumberOfLanguages;
 }
 
diff --git a/apps/shared/language_controller.h b/apps/shared/language_controller.h
index 746e68e1c..fac81fb7c 100644
--- a/apps/shared/language_controller.h
+++ b/apps/shared/language_controller.h
@@ -17,10 +17,10 @@ public:
   void viewWillAppear() override;
   bool handleEvent(Ion::Events::Event event) override;
 
-  int numberOfRows() override;
+  int numberOfRows() const override;
   KDCoordinate cellHeight() override;
   HighlightCell * reusableCell(int index) override;
-  int reusableCellCount() override;
+  int reusableCellCount() const override;
 
   void willDisplayCellForIndex(HighlightCell * cell, int index) override;
 private:
diff --git a/apps/shared/list_parameter_controller.h b/apps/shared/list_parameter_controller.h
index f719918e6..dead11d22 100644
--- a/apps/shared/list_parameter_controller.h
+++ b/apps/shared/list_parameter_controller.h
@@ -17,7 +17,7 @@ public:
   void setRecord(Ion::Storage::Record record);
   void didBecomeFirstResponder() override;
   void viewWillAppear() override;
-  int numberOfRows() override { return totalNumberOfCells(); }
+  int numberOfRows() const override { return totalNumberOfCells(); }
 
   // ListViewDataSource
   KDCoordinate rowHeight(int j) override { return Metric::ParameterCellHeight; }
diff --git a/apps/shared/range_parameter_controller.cpp b/apps/shared/range_parameter_controller.cpp
index fd45e352a..95779d24c 100644
--- a/apps/shared/range_parameter_controller.cpp
+++ b/apps/shared/range_parameter_controller.cpp
@@ -27,7 +27,7 @@ const char * RangeParameterController::title() {
   return I18n::translate(I18n::Message::Axis);
 }
 
-int RangeParameterController::numberOfRows() {
+int RangeParameterController::numberOfRows() const {
   return k_numberOfTextCell+2;
 }
 
diff --git a/apps/shared/range_parameter_controller.h b/apps/shared/range_parameter_controller.h
index b787476a1..63280ad73 100644
--- a/apps/shared/range_parameter_controller.h
+++ b/apps/shared/range_parameter_controller.h
@@ -11,7 +11,7 @@ class RangeParameterController : public FloatParameterController<float> {
 public:
   RangeParameterController(Responder * parentResponder, InputEventHandlerDelegate * inputEventHandlerDelegate, InteractiveCurveViewRange * interactiveCurveViewRange);
   const char * title() override;
-  int numberOfRows() override;
+  int numberOfRows() const override;
   int typeAtLocation(int i, int j) override;
   void willDisplayCellForIndex(HighlightCell * cell, int index) override;
   bool textFieldDidFinishEditing(TextField * textField, const char * text, Ion::Events::Event event) override;
diff --git a/apps/shared/store_controller.cpp b/apps/shared/store_controller.cpp
index c0a42986e..876b7682e 100644
--- a/apps/shared/store_controller.cpp
+++ b/apps/shared/store_controller.cpp
@@ -106,7 +106,7 @@ bool StoreController::textFieldDidAbortEditing(TextField * textField) {
 }
 
 
-int StoreController::numberOfColumns() {
+int StoreController::numberOfColumns() const {
   return DoublePairStore::k_numberOfColumnsPerSeries * DoublePairStore::k_numberOfSeries;
 }
 
@@ -221,7 +221,7 @@ double StoreController::dataAtLocation(int columnIndex, int rowIndex) {
   return m_store->get(seriesAtColumn(columnIndex), columnIndex%DoublePairStore::k_numberOfColumnsPerSeries, rowIndex-1);
 }
 
-int StoreController::numberOfElementsInColumn(int columnIndex) {
+int StoreController::numberOfElementsInColumn(int columnIndex) const {
   return m_store->numberOfPairsOfSeries(seriesAtColumn(columnIndex));
 }
 
diff --git a/apps/shared/store_controller.h b/apps/shared/store_controller.h
index 1e96bb918..3492aebe7 100644
--- a/apps/shared/store_controller.h
+++ b/apps/shared/store_controller.h
@@ -28,7 +28,7 @@ public:
   bool textFieldDidAbortEditing(TextField * textField) override;
 
   // TableViewDataSource
-  int numberOfColumns() override;
+  int numberOfColumns() const override;
   KDCoordinate columnWidth(int i) override;
   KDCoordinate cumulatedWidthFromIndex(int i) override;
   int indexFromCumulatedWidth(KDCoordinate offsetX) override;
@@ -84,7 +84,7 @@ private:
     return m_contentView.dataView();
   }
   bool cellAtLocationIsEditable(int columnIndex, int rowIndex) override;
-  int numberOfElementsInColumn(int columnIndex) override;
+  int numberOfElementsInColumn(int columnIndex) const override;
   int maxNumberOfElements() const override {
     return DoublePairStore::k_maxNumberOfPairs;
   };
diff --git a/apps/shared/store_parameter_controller.h b/apps/shared/store_parameter_controller.h
index fa3212778..8480c7370 100644
--- a/apps/shared/store_parameter_controller.h
+++ b/apps/shared/store_parameter_controller.h
@@ -18,7 +18,7 @@ public:
   const char * title() override;
   bool handleEvent(Ion::Events::Event event) override;
   void didBecomeFirstResponder() override;
-  int numberOfRows() override { return k_totalNumberOfCell; }
+  int numberOfRows() const override { return k_totalNumberOfCell; }
   KDCoordinate rowHeight(int j) override { return Metric::ParameterCellHeight; }
   KDCoordinate cumulatedHeightFromIndex(int j) override;
   int indexFromCumulatedHeight(KDCoordinate offsetY) override;
diff --git a/apps/shared/values_controller.cpp b/apps/shared/values_controller.cpp
index bab758087..590c51a02 100644
--- a/apps/shared/values_controller.cpp
+++ b/apps/shared/values_controller.cpp
@@ -40,7 +40,7 @@ const char * ValuesController::title() {
   return I18n::translate(I18n::Message::ValuesTab);
 }
 
-int ValuesController::numberOfColumns() {
+int ValuesController::numberOfColumns() const {
   if (m_numberOfColumnsNeedUpdate) {
     updateNumberOfColumns();
     m_numberOfColumnsNeedUpdate = false;
@@ -246,11 +246,11 @@ double ValuesController::dataAtLocation(int columnIndex, int rowIndex) {
   return intervalAtColumn(columnIndex)->element(rowIndex-1);
 }
 
-int ValuesController::numberOfElementsInColumn(int columnIndex) {
-  return intervalAtColumn(columnIndex)->numberOfElements();
+int ValuesController::numberOfElementsInColumn(int columnIndex) const {
+  return const_cast<ValuesController *>(this)->intervalAtColumn(columnIndex)->numberOfElements();
 }
 
-void ValuesController::updateNumberOfColumns() {
+void ValuesController::updateNumberOfColumns() const {
   m_numberOfColumns = 1+functionStore()->numberOfActiveFunctions();
 }
 
diff --git a/apps/shared/values_controller.h b/apps/shared/values_controller.h
index f86c02e34..b831e17bf 100644
--- a/apps/shared/values_controller.h
+++ b/apps/shared/values_controller.h
@@ -17,7 +17,7 @@ class ValuesController : public EditableCellTableViewController, public ButtonRo
 public:
   ValuesController(Responder * parentResponder, ButtonRowController * header);
   const char * title() override;
-  int numberOfColumns() override;
+  int numberOfColumns() const override;
   virtual bool handleEvent(Ion::Events::Event event) override;
   void didBecomeFirstResponder() override;
   void willExitResponderChain(Responder * nextFirstResponder) override;
@@ -48,13 +48,13 @@ protected:
   void setupAbscissaCellsAndTitleCells(InputEventHandlerDelegate * inputEventHandlerDelegate);
   StackViewController * stackController() const;
   bool setDataAtLocation(double floatBody, int columnIndex, int rowIndex) override;
-  virtual void updateNumberOfColumns();
+  virtual void updateNumberOfColumns() const;
   virtual FunctionStore * functionStore() const;
   virtual Ion::Storage::Record recordAtColumn(int i);
-  int numberOfElementsInColumn(int columnIndex) override;
+  int numberOfElementsInColumn(int columnIndex) const override;
   SelectableTableView * selectableTableView() override { return &m_selectableTableView; }
-  int m_numberOfColumns;
-  bool m_numberOfColumnsNeedUpdate;
+  mutable int m_numberOfColumns;
+  mutable bool m_numberOfColumnsNeedUpdate;
   SelectableTableView m_selectableTableView;
 private:
   virtual void setStartEndMessages(Shared::IntervalParameterController * controller, int column) = 0;
diff --git a/apps/shared/values_function_parameter_controller.h b/apps/shared/values_function_parameter_controller.h
index 8e2fabc02..a39dbed49 100644
--- a/apps/shared/values_function_parameter_controller.h
+++ b/apps/shared/values_function_parameter_controller.h
@@ -20,13 +20,13 @@ public:
   const char * title() override;
   void viewWillAppear() override;
   void didBecomeFirstResponder() override;
-  virtual int numberOfRows() override { return 1; }
+  virtual int numberOfRows() const override { return 1; }
   KDCoordinate cellHeight() override { return Metric::ParameterCellHeight; }
   virtual HighlightCell * reusableCell(int index) override {
     assert(index == 0);
     return &m_copyColumn;
   }
-  virtual int reusableCellCount() override { return 1; }
+  virtual int reusableCellCount() const override { return 1; }
   void setRecord(Ion::Storage::Record record) { m_record = record; }
 protected:
   MessageTableCellWithChevron m_copyColumn;
diff --git a/apps/shared/values_parameter_controller.cpp b/apps/shared/values_parameter_controller.cpp
index 224b10d46..272808ae9 100644
--- a/apps/shared/values_parameter_controller.cpp
+++ b/apps/shared/values_parameter_controller.cpp
@@ -78,7 +78,7 @@ bool ValuesParameterController::handleEvent(Ion::Events::Event event) {
   return false;
 }
 
-int ValuesParameterController::numberOfRows() {
+int ValuesParameterController::numberOfRows() const {
   return k_totalNumberOfCell;
 };
 
@@ -89,7 +89,7 @@ HighlightCell * ValuesParameterController::reusableCell(int index) {
   return cells[index];
 }
 
-int ValuesParameterController::reusableCellCount() {
+int ValuesParameterController::reusableCellCount() const {
   return k_totalNumberOfCell;
 }
 
diff --git a/apps/shared/values_parameter_controller.h b/apps/shared/values_parameter_controller.h
index 206b4e041..5cc842f72 100644
--- a/apps/shared/values_parameter_controller.h
+++ b/apps/shared/values_parameter_controller.h
@@ -14,10 +14,10 @@ public:
   bool handleEvent(Ion::Events::Event event) override;
   void willDisplayCellForIndex(HighlightCell * cell, int index) override;
   void didBecomeFirstResponder() override;
-  int numberOfRows() override;
+  int numberOfRows() const override;
   KDCoordinate cellHeight() override;
   HighlightCell * reusableCell(int index) override;
-  int reusableCellCount() override;
+  int reusableCellCount() const override;
 private:
 #if COPY_COLUMN
   constexpr static int k_totalNumberOfCell = 3;
diff --git a/apps/solver/equation_models_parameter_controller.cpp b/apps/solver/equation_models_parameter_controller.cpp
index 2a769c05c..2ed3f6ac7 100644
--- a/apps/solver/equation_models_parameter_controller.cpp
+++ b/apps/solver/equation_models_parameter_controller.cpp
@@ -60,7 +60,7 @@ bool EquationModelsParameterController::handleEvent(Ion::Events::Event event) {
   return false;
 }
 
-int EquationModelsParameterController::numberOfRows() {
+int EquationModelsParameterController::numberOfRows() const {
   return k_numberOfExpressionCells+1;
 };
 
diff --git a/apps/solver/equation_models_parameter_controller.h b/apps/solver/equation_models_parameter_controller.h
index ecf57f315..bb6812cb1 100644
--- a/apps/solver/equation_models_parameter_controller.h
+++ b/apps/solver/equation_models_parameter_controller.h
@@ -16,7 +16,7 @@ public:
   void viewWillAppear() override;
   void didBecomeFirstResponder() override;
   bool handleEvent(Ion::Events::Event event) override;
-  int numberOfRows() override;
+  int numberOfRows() const override;
   KDCoordinate rowHeight(int j) override;
   KDCoordinate cumulatedHeightFromIndex(int j) override;
   int indexFromCumulatedHeight(KDCoordinate offsetY) override;
diff --git a/apps/solver/interval_controller.cpp b/apps/solver/interval_controller.cpp
index a1ab7e131..cb452a0ce 100644
--- a/apps/solver/interval_controller.cpp
+++ b/apps/solver/interval_controller.cpp
@@ -59,7 +59,7 @@ const char * IntervalController::title() {
   return I18n::translate(I18n::Message::SearchInverval);
 }
 
-int IntervalController::numberOfRows() {
+int IntervalController::numberOfRows() const {
   return k_maxNumberOfCells+1;
 }
 
diff --git a/apps/solver/interval_controller.h b/apps/solver/interval_controller.h
index acf1ddc34..206f86fd1 100644
--- a/apps/solver/interval_controller.h
+++ b/apps/solver/interval_controller.h
@@ -12,7 +12,7 @@ public:
   IntervalController(Responder * parentResponder, InputEventHandlerDelegate * inputEventHandlerDelegate, EquationStore * equationStore);
   const char * title() override;
   View * view() override { return &m_contentView; }
-  int numberOfRows() override;
+  int numberOfRows() const override;
   void willDisplayCellForIndex(HighlightCell * cell, int index) override;
 private:
   HighlightCell * reusableParameterCell(int index, int type) override;
diff --git a/apps/solver/list_controller.h b/apps/solver/list_controller.h
index 5d54369e0..5642963b3 100644
--- a/apps/solver/list_controller.h
+++ b/apps/solver/list_controller.h
@@ -19,7 +19,7 @@ public:
   int numberOfButtons(ButtonRowController::Position position) const override;
   Button * buttonAtIndex(int index, ButtonRowController::Position position) const override;
   /* ListViewDataSource */
-  int numberOfRows() override { return numberOfExpressionRows(); }
+  int numberOfRows() const override { return numberOfExpressionRows(); }
   KDCoordinate rowHeight(int j) override{ return ExpressionModelListController::memoizedRowHeight(j); }
   KDCoordinate cumulatedHeightFromIndex(int j) override { return ExpressionModelListController::memoizedCumulatedHeightFromIndex(j); }
   int indexFromCumulatedHeight(KDCoordinate offsetY) override { return ExpressionModelListController::memoizedIndexFromCumulatedHeight(offsetY); }
diff --git a/apps/solver/solutions_controller.cpp b/apps/solver/solutions_controller.cpp
index 3d05a43b0..8ec20a4a5 100644
--- a/apps/solver/solutions_controller.cpp
+++ b/apps/solver/solutions_controller.cpp
@@ -149,11 +149,11 @@ Responder * SolutionsController::defaultController() {
 
 /* TableViewDataSource */
 
-int SolutionsController::numberOfRows() {
+int SolutionsController::numberOfRows() const {
   return m_equationStore->numberOfSolutions();
 }
 
-int SolutionsController::numberOfColumns() {
+int SolutionsController::numberOfColumns() const {
   return 2;
 }
 
diff --git a/apps/solver/solutions_controller.h b/apps/solver/solutions_controller.h
index 172faf761..33208d7c2 100644
--- a/apps/solver/solutions_controller.h
+++ b/apps/solver/solutions_controller.h
@@ -20,8 +20,8 @@ public:
   virtual I18n::Message emptyMessage() override;
   virtual Responder * defaultController() override;
   /* TableViewDataSource */
-  int numberOfRows() override;
-  int numberOfColumns() override;
+  int numberOfRows() const override;
+  int numberOfColumns() const override;
   void willDisplayCellAtLocation(HighlightCell * cell, int i, int j) override;
   KDCoordinate columnWidth(int i) override;
   KDCoordinate rowHeight(int j) override;
diff --git a/apps/statistics/calculation_controller.cpp b/apps/statistics/calculation_controller.cpp
index 627716461..bbf195288 100644
--- a/apps/statistics/calculation_controller.cpp
+++ b/apps/statistics/calculation_controller.cpp
@@ -50,7 +50,7 @@ Responder * CalculationController::defaultController() {
 
 // TableViewDataSource
 
-int CalculationController::numberOfColumns() {
+int CalculationController::numberOfColumns() const {
   return 1 + m_store->numberOfNonEmptySeries();
 }
 
diff --git a/apps/statistics/calculation_controller.h b/apps/statistics/calculation_controller.h
index 653ac69d4..9f5075adc 100644
--- a/apps/statistics/calculation_controller.h
+++ b/apps/statistics/calculation_controller.h
@@ -25,8 +25,8 @@ public:
   Responder * defaultController() override;
 
   // TableViewDataSource
-  int numberOfRows() override { return k_totalNumberOfRows; }
-  int numberOfColumns() override;
+  int numberOfRows() const override { return k_totalNumberOfRows; }
+  int numberOfColumns() const override;
   void willDisplayCellAtLocation(HighlightCell * cell, int i, int j) override;
   KDCoordinate columnWidth(int i) override;
   KDCoordinate rowHeight(int j) override { return k_cellHeight; }
diff --git a/apps/statistics/histogram_parameter_controller.h b/apps/statistics/histogram_parameter_controller.h
index 7c12a4fa4..7688b7b27 100644
--- a/apps/statistics/histogram_parameter_controller.h
+++ b/apps/statistics/histogram_parameter_controller.h
@@ -11,7 +11,7 @@ class HistogramParameterController : public Shared::FloatParameterController<dou
 public:
   HistogramParameterController(Responder * parentResponder, InputEventHandlerDelegate * inputEventHandlerDelegateApp, Store * store);
   const char * title() override;
-  int numberOfRows() override { return 1+k_numberOfCells; }
+  int numberOfRows() const override { return 1+k_numberOfCells; }
   void willDisplayCellForIndex(HighlightCell * cell, int index) override;
 private:
   constexpr static int k_numberOfCells = 2;
diff --git a/apps/variable_box_controller.cpp b/apps/variable_box_controller.cpp
index c286322d6..fa857dccb 100644
--- a/apps/variable_box_controller.cpp
+++ b/apps/variable_box_controller.cpp
@@ -69,7 +69,7 @@ bool VariableBoxController::handleEvent(Ion::Events::Event event) {
   return NestedMenuController::handleEvent(event);
 }
 
-int VariableBoxController::numberOfRows() {
+int VariableBoxController::numberOfRows() const {
   switch (m_currentPage) {
     case Page::RootMenu:
       return k_numberOfMenuRows;
diff --git a/apps/variable_box_controller.h b/apps/variable_box_controller.h
index 8dc7eb6cb..439afc4e2 100644
--- a/apps/variable_box_controller.h
+++ b/apps/variable_box_controller.h
@@ -19,7 +19,7 @@ public:
   bool handleEvent(Ion::Events::Event event) override;
 
   //ListViewDataSource
-  int numberOfRows() override;
+  int numberOfRows() const override;
   int reusableCellCount(int type) override;
   void willDisplayCellForIndex(HighlightCell * cell, int index) override;
   KDCoordinate rowHeight(int j) override;
diff --git a/escher/include/escher/list_view_data_source.h b/escher/include/escher/list_view_data_source.h
index 7af0648d0..62ad562e9 100644
--- a/escher/include/escher/list_view_data_source.h
+++ b/escher/include/escher/list_view_data_source.h
@@ -8,7 +8,7 @@ class ListViewDataSource : public TableViewDataSource {
 public:
   virtual KDCoordinate cellWidth();
   KDCoordinate columnWidth(int i) override;
-  int numberOfColumns() override;
+  int numberOfColumns() const override;
   void willDisplayCellAtLocation(HighlightCell * cell, int x, int y) override;
   int indexFromCumulatedWidth(KDCoordinate offsetX) override;
   KDCoordinate cumulatedWidthFromIndex(int i) override;
diff --git a/escher/include/escher/nested_menu_controller.h b/escher/include/escher/nested_menu_controller.h
index d886f4212..0ff69acfe 100644
--- a/escher/include/escher/nested_menu_controller.h
+++ b/escher/include/escher/nested_menu_controller.h
@@ -27,7 +27,7 @@ protected:
     class State {
     public:
       State(int selectedRow = -1, KDCoordinate verticalScroll = 0);
-      bool isNull();
+      bool isNull() const;
       int selectedRow() { return m_selectedRow; }
       KDCoordinate verticalScroll() { return m_verticalScroll; }
     private:
@@ -37,7 +37,7 @@ protected:
     void push(int selectedRow, KDCoordinate verticalScroll);
     State * stateAtIndex(int index);
     State pop();
-    int depth();
+    int depth() const;
     void resetStack();
   private:
     constexpr static int k_maxModelTreeDepth = 3;
@@ -59,7 +59,7 @@ protected:
 
   static constexpr int LeafCellType = 0;
   static constexpr int NodeCellType = 1;
-  int stackDepth();
+  int stackDepth() const;
   bool handleEventForRow(Ion::Events::Event event, int selectedRow);
   virtual bool selectSubMenu(int selectedRow);
   virtual bool returnToPreviousMenu();
diff --git a/escher/include/escher/simple_list_view_data_source.h b/escher/include/escher/simple_list_view_data_source.h
index 16b38a7ec..99d00306c 100644
--- a/escher/include/escher/simple_list_view_data_source.h
+++ b/escher/include/escher/simple_list_view_data_source.h
@@ -11,7 +11,7 @@ public:
   KDCoordinate cumulatedHeightFromIndex(int j) override;
   int indexFromCumulatedHeight(KDCoordinate offsetY) override;
   virtual HighlightCell * reusableCell(int index) = 0;
-  virtual int reusableCellCount() = 0;
+  virtual int reusableCellCount() const = 0;
   HighlightCell * reusableCell(int index, int type) override;
   int reusableCellCount(int type) override;
   int typeAtLocation(int i, int j) override;
diff --git a/escher/include/escher/simple_table_view_data_source.h b/escher/include/escher/simple_table_view_data_source.h
index e543a61f2..22bce020e 100644
--- a/escher/include/escher/simple_table_view_data_source.h
+++ b/escher/include/escher/simple_table_view_data_source.h
@@ -15,7 +15,7 @@ public:
   int indexFromCumulatedWidth(KDCoordinate offsetX) override;
   int indexFromCumulatedHeight(KDCoordinate offsetY) override;
   virtual HighlightCell * reusableCell(int index) = 0;
-  virtual int reusableCellCount() = 0;
+  virtual int reusableCellCount() const = 0;
   HighlightCell * reusableCell(int index, int type) override;
   int reusableCellCount(int type) override;
   int typeAtLocation(int i, int j) override;
diff --git a/escher/include/escher/table_view_data_source.h b/escher/include/escher/table_view_data_source.h
index 091ce59a0..ab20509b9 100644
--- a/escher/include/escher/table_view_data_source.h
+++ b/escher/include/escher/table_view_data_source.h
@@ -6,8 +6,8 @@
 
 class TableViewDataSource {
 public:
-  virtual int numberOfRows() = 0;
-  virtual int numberOfColumns() = 0;
+  virtual int numberOfRows() const = 0;
+  virtual int numberOfColumns() const = 0;
   virtual void willDisplayCellAtLocation(HighlightCell * cell, int i, int j);
   virtual KDCoordinate columnWidth(int i) = 0;
   virtual KDCoordinate rowHeight(int j) = 0;
@@ -26,4 +26,4 @@ public:
   virtual int typeAtLocation(int i, int j) = 0;
 };
 
-#endif
\ No newline at end of file
+#endif
diff --git a/escher/include/escher/toolbox.h b/escher/include/escher/toolbox.h
index 8003d31e8..7737c1369 100644
--- a/escher/include/escher/toolbox.h
+++ b/escher/include/escher/toolbox.h
@@ -14,7 +14,7 @@ public:
   void viewWillAppear() override;
 
   //ListViewDataSource
-  int numberOfRows() override;
+  int numberOfRows() const override;
   int reusableCellCount(int type) override;
   void willDisplayCellForIndex(HighlightCell * cell, int index) override;
   int typeAtLocation(int i, int j) override;
@@ -24,10 +24,10 @@ protected:
   bool selectSubMenu(int selectedRow) override;
   bool returnToPreviousMenu() override;
   virtual int maxNumberOfDisplayedRows() = 0;
-  virtual const ToolboxMessageTree * rootModel() = 0;
+  virtual const ToolboxMessageTree * rootModel() const = 0;
   virtual MessageTableCellWithMessage * leafCellAtIndex(int index) override = 0;
   virtual MessageTableCellWithChevron * nodeCellAtIndex(int index) override = 0;
-  ToolboxMessageTree * m_messageTreeModel;
+  mutable ToolboxMessageTree * m_messageTreeModel;
   /* m_messageTreeModel points at the messageTree of the tree (describing the
    * whole model) where we are located. It enables to know which rows are leaves
    * and which are subtrees. */
diff --git a/escher/src/list_view_data_source.cpp b/escher/src/list_view_data_source.cpp
index e5e078076..1a930d382 100644
--- a/escher/src/list_view_data_source.cpp
+++ b/escher/src/list_view_data_source.cpp
@@ -8,7 +8,7 @@ KDCoordinate ListViewDataSource::columnWidth(int i) {
   return cellWidth();
 }
 
-int ListViewDataSource::numberOfColumns() {
+int ListViewDataSource::numberOfColumns() const {
   return 1;
 }
 
diff --git a/escher/src/nested_menu_controller.cpp b/escher/src/nested_menu_controller.cpp
index 2ba845a67..d5a147f67 100644
--- a/escher/src/nested_menu_controller.cpp
+++ b/escher/src/nested_menu_controller.cpp
@@ -12,7 +12,7 @@ NestedMenuController::Stack::State::State(int selectedRow, KDCoordinate vertical
 {
 }
 
-bool NestedMenuController::Stack::State::isNull(){
+bool NestedMenuController::Stack::State::isNull() const {
   if (m_selectedRow == -1) {
     return true;
   }
@@ -34,7 +34,7 @@ NestedMenuController::Stack::State * NestedMenuController::Stack::stateAtIndex(i
   return &m_statesStack[index];
 }
 
-int NestedMenuController::Stack::depth() {
+int NestedMenuController::Stack::depth() const {
   int depth = 0;
   for (int i = 0; i < k_maxModelTreeDepth; i++) {
     depth += (!m_statesStack[i].isNull());
@@ -131,7 +131,7 @@ HighlightCell * NestedMenuController::reusableCell(int index, int type) {
   return nodeCellAtIndex(index);
 }
 
-int NestedMenuController::stackDepth() {
+int NestedMenuController::stackDepth() const {
   return m_stack.depth();
 }
 
diff --git a/escher/src/toolbox.cpp b/escher/src/toolbox.cpp
index 4f9298358..c2ebf0603 100644
--- a/escher/src/toolbox.cpp
+++ b/escher/src/toolbox.cpp
@@ -13,7 +13,7 @@ void Toolbox::viewWillAppear() {
   NestedMenuController::viewWillAppear();
 }
 
-int Toolbox::numberOfRows() {
+int Toolbox::numberOfRows() const {
   if (m_messageTreeModel == nullptr) {
     m_messageTreeModel = (ToolboxMessageTree *)rootModel();
   }