--- a/Applications/Samples/SampleApplicationBase.h	Thu Oct 18 10:54:46 2018 +0200
+++ b/Applications/Samples/SampleApplicationBase.h	Thu Oct 18 19:29:14 2018 +0200
@@ -22,7 +22,7 @@
 #pragma once
 
 #include "../../Applications/IStoneApplication.h"
-#include "../../Framework/Widgets/LayerWidget.h"
+#include "../../Framework/Widgets/WorldSceneWidget.h"
 
 #if ORTHANC_ENABLE_WASM==1
 #include "../../Platforms/Wasm/WasmPlatformApplicationAdapter.h"
@@ -42,7 +42,7 @@
     {
     protected:
       BaseCommandBuilder commandBuilder_;
-      LayerWidget*       mainWidget_;   // ownership is transfered to the application context
+      WorldSceneWidget*  mainWidget_;   // ownership is transfered to the application context
 
     public:
       virtual void Initialize(StoneApplicationContext* context,

--- a/Applications/Samples/SimpleViewerApplicationSingleFile.h	Thu Oct 18 10:54:46 2018 +0200
+++ b/Applications/Samples/SimpleViewerApplicationSingleFile.h	Thu Oct 18 19:29:14 2018 +0200
@@ -351,9 +351,10 @@
           LoadThumbnailForSeries(seriesId, instancesIdsPerSeriesId_[seriesId][0]);
 
           // if this is the first thumbnail loaded, load the first instance in the mainWidget
-          if (mainWidget_->GetLayerCount() == 0)
+          LayerWidget& widget = *dynamic_cast<LayerWidget*>(mainWidget_);
+          if (widget.GetLayerCount() == 0)
           {
-            smartLoader_->SetFrameInWidget(*mainWidget_, 0, instancesIdsPerSeriesId_[seriesId][0], 0);
+            smartLoader_->SetFrameInWidget(widget, 0, instancesIdsPerSeriesId_[seriesId][0], 0);
           }
         }
       }
@@ -381,7 +382,8 @@
 
       void SelectSeriesInMainViewport(const std::string& seriesId)
       {
-        smartLoader_->SetFrameInWidget(*mainWidget_, 0, instancesIdsPerSeriesId_[seriesId][0], 0);
+        LayerWidget& widget = *dynamic_cast<LayerWidget*>(mainWidget_);
+        smartLoader_->SetFrameInWidget(widget, 0, instancesIdsPerSeriesId_[seriesId][0], 0);
       }
 
       virtual void OnPushButton1Clicked() {}

--- a/Applications/Samples/SingleFrameApplication.h	Thu Oct 18 10:54:46 2018 +0200
+++ b/Applications/Samples/SingleFrameApplication.h	Thu Oct 18 19:29:14 2018 +0200
@@ -140,6 +140,12 @@
           }   
         }
       }
+
+
+      LayerWidget& GetMainWidget()
+      {
+        return *dynamic_cast<LayerWidget*>(mainWidget_);
+      }
       
 
       void SetSlice(size_t index)
@@ -150,7 +156,7 @@
           slice_ = index;
           
 #if 1
-          mainWidget_->SetSlice(source_->GetSlice(slice_).GetGeometry());
+          GetMainWidget().SetSlice(source_->GetSlice(slice_).GetGeometry());
 #else
           // TEST for scene extents - Rotate the axes
           double a = 15.0 / 180.0 * M_PI;
@@ -181,7 +187,7 @@
           SetSlice(source_->GetSliceCount() / 2);
         }
 
-        mainWidget_->FitContent();
+        GetMainWidget().FitContent();
       }
       
       std::auto_ptr<Interactor>         mainWidgetInteractor_;
@@ -238,7 +244,7 @@
         source_ = layer.get();
         layer->LoadFrame(instance, frame);
         layer->RegisterObserverCallback(new Callable<SingleFrameApplication, ILayerSource::GeometryReadyMessage>(*this, &SingleFrameApplication::OnMainWidgetGeometryReady));
-        mainWidget_->AddLayer(layer.release());
+        GetMainWidget().AddLayer(layer.release());
 
         RenderStyle s;
 
@@ -247,11 +253,11 @@
           s.interpolation_ = ImageInterpolation_Bilinear;
         }
 
-        mainWidget_->SetLayerStyle(0, s);
-        mainWidget_->SetTransmitMouseOver(true);
+        GetMainWidget().SetLayerStyle(0, s);
+        GetMainWidget().SetTransmitMouseOver(true);
 
         mainWidgetInteractor_.reset(new Interactor(*this));
-        mainWidget_->SetInteractor(*mainWidgetInteractor_);
+        GetMainWidget().SetInteractor(*mainWidgetInteractor_);
       }
     };
 

--- a/Applications/Samples/SingleFrameEditorApplication.h	Thu Oct 18 10:54:46 2018 +0200
+++ b/Applications/Samples/SingleFrameEditorApplication.h	Thu Oct 18 19:29:14 2018 +0200
@@ -24,12 +24,41 @@
 #include "SampleApplicationBase.h"
 
 #include "../../Framework/Layers/OrthancFrameLayerSource.h"
-#include "../../Framework/Widgets/LayerWidget.h"
 
 #include <Core/Logging.h>
 
 namespace OrthancStone
 {
+
+  class GrayscaleBitmapStack :
+    public WorldSceneWidget,
+    public IObservable
+  {
+  public:
+    typedef OriginMessage<MessageType_Widget_GeometryChanged, GrayscaleBitmapStack> GeometryChangedMessage;
+    typedef OriginMessage<MessageType_Widget_ContentChanged, GrayscaleBitmapStack> ContentChangedMessage;
+
+  protected:
+    virtual Extent2D GetSceneExtent()
+    {
+    }
+
+    virtual bool RenderScene(CairoContext& context,
+                             const ViewportGeometry& view)
+    {
+    }
+
+  public:
+    GrayscaleBitmapStack(MessageBroker& broker,
+                         const std::string& name) :
+      WorldSceneWidget(name),
+      IObservable(broker)
+    {
+    }
+  
+  };
+
+  
   namespace Samples
   {
     class SingleFrameEditorApplication :
@@ -94,12 +123,9 @@
         {
           if (statusBar != NULL)
           {
-            Vector p = dynamic_cast<LayerWidget&>(widget).GetSlice().MapSliceToWorldCoordinates(x, y);
-            
             char buf[64];
-            sprintf(buf, "X = %.02f Y = %.02f Z = %.02f (in cm)",
-                    p[0] / 10.0, p[1] / 10.0, p[2] / 10.0);
-            //statusBar->SetMessage(buf);
+            sprintf(buf, "X = %.02f Y = %.02f (in cm)", x / 10.0, y / 10.0);
+            statusBar->SetMessage(buf);
           }
         }
 
@@ -151,9 +177,8 @@
         }
       };
 
-      void OnGeometryChanged(const LayerWidget::GeometryChangedMessage& message)
+      void OnGeometryChanged(const GrayscaleBitmapStack::GeometryChangedMessage& message)
       {
-        mainWidget_->SetSlice(source_->GetSlice(slice_).GetGeometry());
         mainWidget_->FitContent();
       }
       
@@ -205,13 +230,12 @@
         int frame = parameters["frame"].as<unsigned int>();
 
         orthancApiClient_.reset(new OrthancApiClient(IObserver::broker_, context_->GetWebService()));
-        mainWidget_ = new LayerWidget(broker_, "main-widget");
+        mainWidget_ = new GrayscaleBitmapStack(broker_, "main-widget");
 
-        std::auto_ptr<OrthancFrameLayerSource> layer(new OrthancFrameLayerSource(broker_, *orthancApiClient_));
-        source_ = layer.get();
-        layer->LoadFrame(instance, frame);
-        mainWidget_->RegisterObserverCallback(new Callable<SingleFrameEditorApplication, LayerWidget::GeometryChangedMessage>(*this, &SingleFrameEditorApplication::OnGeometryChanged));
-        mainWidget_->AddLayer(layer.release());
+        dynamic_cast<GrayscaleBitmapStack*>(mainWidget_)->RegisterObserverCallback(
+          new Callable<SingleFrameEditorApplication,
+          GrayscaleBitmapStack::GeometryChangedMessage>
+          (*this, &SingleFrameEditorApplication::OnGeometryChanged));
 
         mainWidget_->SetTransmitMouseOver(true);