--- a/OrthancStone/Sources/Scene2DViewport/MeasureCommands.h	Thu Oct 08 14:16:47 2026 +0200
+++ b/OrthancStone/Sources/Scene2DViewport/MeasureCommands.h	Thu Oct 08 14:27:50 2026 +0200
@@ -22,11 +22,10 @@
 #pragma once
 
 #include "../Viewport/IViewport.h"
-
-// to be moved into Stone
 #include "MeasureTool.h"
 #include "LineMeasureTool.h"
 #include "AngleMeasureTool.h"
+#include "UndoStack.h"
 
 #include <boost/shared_ptr.hpp>
 #include <boost/weak_ptr.hpp>
@@ -34,7 +33,7 @@
 
 namespace OrthancStone
 {
-  class MeasureCommand : public boost::noncopyable
+  class MeasureCommand : public UndoStack::ICommand
   {
   protected:
     boost::weak_ptr<IViewport> viewport_;

--- a/OrthancStone/Sources/Scene2DViewport/UndoStack.cpp	Thu Oct 08 14:16:47 2026 +0200
+++ b/OrthancStone/Sources/Scene2DViewport/UndoStack.cpp	Thu Oct 08 14:27:50 2026 +0200
@@ -22,23 +22,17 @@
 
 #include "UndoStack.h"
 
-#include "MeasureCommands.h"
-
 #include "../StoneException.h"
 
 namespace OrthancStone
 {
-  UndoStack::UndoStack() : numAppliedCommands_(0)
-  {}
-
-  void UndoStack::PushCommand(const boost::shared_ptr<MeasureCommand>& command)
+  void UndoStack::PushCommand(const boost::shared_ptr<ICommand>& command)
   {
     commandStack_.erase(
       commandStack_.begin() + numAppliedCommands_,
       commandStack_.end());
 
-    ORTHANC_ASSERT(std::find(commandStack_.begin(), commandStack_.end(), command)
-      == commandStack_.end(), "Duplicate command");
+    ORTHANC_ASSERT(std::find(commandStack_.begin(), commandStack_.end(), command) == commandStack_.end(), "Duplicate command");
     commandStack_.push_back(command);
     numAppliedCommands_++;
   }
@@ -66,5 +60,4 @@
   {
     return numAppliedCommands_ < commandStack_.size();
   }
-
 }

--- a/OrthancStone/Sources/Scene2DViewport/UndoStack.h	Thu Oct 08 14:16:47 2026 +0200
+++ b/OrthancStone/Sources/Scene2DViewport/UndoStack.h	Thu Oct 08 14:27:50 2026 +0200
@@ -24,17 +24,42 @@
 
 #include <boost/noncopyable.hpp>
 #include <boost/shared_ptr.hpp>
+#include <vector>
 
-#include <vector>
 
 namespace OrthancStone
 {
-  class MeasureCommand;
-
   class UndoStack : public boost::noncopyable
   {
   public:
-    UndoStack();
+    class ICommand : public boost::noncopyable
+    {
+    public:
+      virtual ~ICommand()
+      {
+      }
+
+      virtual void Undo() = 0;
+
+      virtual void Redo() = 0;
+    };
+
+  private:
+    std::vector<boost::shared_ptr<ICommand> > commandStack_;
+
+    /**
+    This is always between >= 0 and <= undoStack_.size() and gives the
+    position where the controller is in the undo stack.
+    - If numAppliedCommands_ > 0, one can undo
+    - If numAppliedCommands_ < numAppliedCommands_.size(), one can redo
+    */
+    size_t                      numAppliedCommands_;
+
+  public:
+    UndoStack() :
+      numAppliedCommands_(0)
+    {
+    }
 
     /**
     Stores a command :
@@ -44,37 +69,24 @@
     In other words, when a new command is pushed, all the undone (and not
     redone) commands are removed.
     */
-    void PushCommand(const boost::shared_ptr<MeasureCommand>& command);
+    void PushCommand(const boost::shared_ptr<ICommand>& command);
 
     /**
     Undoes the command at the top of the undo stack, or throws if there is no
     command to undo.
-    You can check "CanUndo" first to protect against extraneous redo.
+    You can check "CanUndo()" first to protect against extraneous undo.
     */
     void Undo();
 
     /**
     Redoes the command that is just above the last applied command in the undo
     stack or throws if there is no command to redo.
-    You can check "CanRedo" first to protect against extraneous redo.
+    You can check "CanRedo()" first to protect against extraneous redo.
     */
     void Redo();
 
-    /** selfexpl */
     bool CanUndo() const;
 
-    /** selfexpl */
     bool CanRedo() const;
-  
-  private:
-    std::vector<boost::shared_ptr<MeasureCommand> > commandStack_;
-
-    /**
-    This is always between >= 0 and <= undoStack_.size() and gives the
-    position where the controller is in the undo stack.
-    - If numAppliedCommands_ > 0, one can undo
-    - If numAppliedCommands_ < numAppliedCommands_.size(), one can redo
-    */
-    size_t                      numAppliedCommands_;
   };
 }

--- a/OrthancStone/Sources/Scene2DViewport/ViewportController.cpp	Thu Oct 08 14:16:47 2026 +0200
+++ b/OrthancStone/Sources/Scene2DViewport/ViewportController.cpp	Thu Oct 08 14:27:50 2026 +0200
@@ -38,7 +38,7 @@
     // The controller must be able to cope with this.
   }
 
-  void ViewportController::PushCommand(const boost::shared_ptr<MeasureCommand>& command)
+  void ViewportController::PushCommand(const boost::shared_ptr<UndoStack::ICommand>& command)
   {
     if (undoStackW_)
     {

--- a/OrthancStone/Sources/Scene2DViewport/ViewportController.h	Thu Oct 08 14:16:47 2026 +0200
+++ b/OrthancStone/Sources/Scene2DViewport/ViewportController.h	Thu Oct 08 14:27:50 2026 +0200
@@ -27,6 +27,7 @@
 #include "../Scene2DViewport/IFlexiblePointerTracker.h"
 #include "../Viewport/IViewport.h"
 #include "../Viewport/IViewportInteractor.h"
+#include "UndoStack.h"
 
 #include <Compatibility.h>
 
@@ -35,9 +36,7 @@
 
 namespace OrthancStone
 {
-  class MeasureCommand;
   class MeasureTool;
-  class UndoStack;
 
   const double ARC_RADIUS_CANVAS_COORD = 30.0;
   const double TEXT_CENTER_DISTANCE_CANVAS_COORD = 90;
@@ -163,7 +162,7 @@
 
 
     /** forwarded to the UndoStack */
-    void PushCommand(const boost::shared_ptr<MeasureCommand>& command);
+    void PushCommand(const boost::shared_ptr<UndoStack::ICommand>& command);
 
     /** forwarded to the UndoStack */
     void Undo();