diff --git a/gui/include/DragDropHelper.h b/gui/include/DragDropHelper.h
index 871b84d..17103c4 100644
--- a/gui/include/DragDropHelper.h
+++ b/gui/include/DragDropHelper.h
@@ -53,6 +53,8 @@ public:
 
     QUrl imageTemporaryUrl(const QImage &image) const;
 
+    void setHightlightedDragWidget(VisualizationDragWidget *dragWidget);
+
 private:
     class DragDropHelperPrivate;
     spimpl::unique_impl_ptr<DragDropHelperPrivate> impl;
diff --git a/gui/include/Visualization/VisualizationDragWidget.h b/gui/include/Visualization/VisualizationDragWidget.h
index 3552cef..15924d3 100644
--- a/gui/include/Visualization/VisualizationDragWidget.h
+++ b/gui/include/Visualization/VisualizationDragWidget.h
@@ -13,6 +13,7 @@ public:
 
     virtual QMimeData *mimeData() const = 0;
     virtual bool isDragAllowed() const = 0;
+    virtual void highlightForMerge(bool highlighted) { Q_UNUSED(highlighted); };
 
 protected:
     virtual void mousePressEvent(QMouseEvent *event) override;
diff --git a/gui/include/Visualization/VisualizationGraphWidget.h b/gui/include/Visualization/VisualizationGraphWidget.h
index b0e85c7..a012cb7 100644
--- a/gui/include/Visualization/VisualizationGraphWidget.h
+++ b/gui/include/Visualization/VisualizationGraphWidget.h
@@ -59,6 +59,7 @@ public:
     // VisualisationDragWidget
     QMimeData *mimeData() const override;
     bool isDragAllowed() const override;
+    void highlightForMerge(bool highlighted) override;
 
 signals:
     void synchronize(const SqpRange &range, const SqpRange &oldRange);
diff --git a/gui/src/DragDropHelper.cpp b/gui/src/DragDropHelper.cpp
index 7e91e83..42f83bf 100644
--- a/gui/src/DragDropHelper.cpp
+++ b/gui/src/DragDropHelper.cpp
@@ -29,7 +29,6 @@ struct DragDropScroller::DragDropScrollerPrivate {
     QScrollArea *m_CurrentScrollArea = nullptr;
     std::unique_ptr<QTimer> m_Timer = nullptr;
 
-
     enum class ScrollDirection { up, down, unknown };
     ScrollDirection m_Direction = ScrollDirection::unknown;
 
@@ -148,6 +147,8 @@ struct DragDropHelper::DragDropHelperPrivate {
     QString m_ImageTempUrl; // Temporary file for image url generated by the drag & drop. Not using
                             // QTemporaryFile to have a name which is not generated.
 
+    VisualizationDragWidget *m_HighlightedDragWidget = nullptr;
+
     explicit DragDropHelperPrivate()
             : m_PlaceHolder{std::make_unique<QWidget>()},
               m_DragDropScroller{std::make_unique<DragDropScroller>()}
@@ -176,9 +177,7 @@ struct DragDropHelper::DragDropHelperPrivate {
 };
 
 
-DragDropHelper::DragDropHelper() : impl{spimpl::make_unique_impl<DragDropHelperPrivate>()}
-{
-}
+DragDropHelper::DragDropHelper() : impl{spimpl::make_unique_impl<DragDropHelperPrivate>()} {}
 
 DragDropHelper::~DragDropHelper()
 {
@@ -188,6 +187,7 @@ DragDropHelper::~DragDropHelper()
 void DragDropHelper::resetDragAndDrop()
 {
     setCurrentDragWidget(nullptr);
+    impl->m_HighlightedDragWidget = nullptr;
 }
 
 void DragDropHelper::setCurrentDragWidget(VisualizationDragWidget *dragWidget)
@@ -245,6 +245,18 @@ QUrl DragDropHelper::imageTemporaryUrl(const QImage &image) const
     return QUrl::fromLocalFile(impl->m_ImageTempUrl);
 }
 
+void DragDropHelper::setHightlightedDragWidget(VisualizationDragWidget *dragWidget)
+{
+    if (impl->m_HighlightedDragWidget) {
+        impl->m_HighlightedDragWidget->highlightForMerge(false);
+    }
+
+    if (dragWidget) {
+        impl->m_HighlightedDragWidget = dragWidget;
+        impl->m_HighlightedDragWidget->highlightForMerge(true);
+    }
+}
+
 bool DragDropHelper::checkMimeDataForVisualization(const QMimeData *mimeData,
                                                    VisualizationDragDropContainer *dropContainer)
 {
diff --git a/gui/src/Visualization/VisualizationDragDropContainer.cpp b/gui/src/Visualization/VisualizationDragDropContainer.cpp
index e957a28..4fd4ab6 100644
--- a/gui/src/Visualization/VisualizationDragDropContainer.cpp
+++ b/gui/src/Visualization/VisualizationDragDropContainer.cpp
@@ -294,12 +294,16 @@ void VisualizationDragDropContainer::dragMoveEvent(QDragMoveEvent *event)
                     if (dropIndex != placeHolderIndex) {
                         helper.insertPlaceHolder(impl->m_Layout, dropIndex);
                     }
+
+                    helper.setHightlightedDragWidget(nullptr);
                 }
                 else if (canMerge) {
                     // drop on the middle -> merge
                     if (impl->hasPlaceHolder()) {
                         helper.removePlaceHolder();
                     }
+
+                    helper.setHightlightedDragWidget(dragWidgetHovered);
                 }
             }
             else {
@@ -344,6 +348,7 @@ void VisualizationDragDropContainer::dropEvent(QDropEvent *event)
             event->acceptProposedAction();
 
             helper.removePlaceHolder();
+            helper.setHightlightedDragWidget(nullptr);
 
             emit dropOccured(droppedIndex, event->mimeData());
         }
@@ -351,7 +356,8 @@ void VisualizationDragDropContainer::dropEvent(QDropEvent *event)
             qCWarning(LOG_VisualizationDragDropContainer())
                 << tr("VisualizationDragDropContainer::dropEvent, couldn't drop because the "
                       "placeHolder is not found.");
-            Q_ASSERT(false);
+            sqpApp->dragDropHelper().setHightlightedDragWidget(nullptr);
+            // Q_ASSERT(false);
         }
     }
     else {
diff --git a/gui/src/Visualization/VisualizationGraphWidget.cpp b/gui/src/Visualization/VisualizationGraphWidget.cpp
index 5956f76..676a076 100644
--- a/gui/src/Visualization/VisualizationGraphWidget.cpp
+++ b/gui/src/Visualization/VisualizationGraphWidget.cpp
@@ -73,9 +73,10 @@ VisualizationGraphWidget::VisualizationGraphWidget(const QString &name, QWidget 
             &VisualizationGraphWidget::onMouseRelease);
     connect(ui->widget, &QCustomPlot::mouseMove, this, &VisualizationGraphWidget::onMouseMove);
     connect(ui->widget, &QCustomPlot::mouseWheel, this, &VisualizationGraphWidget::onMouseWheel);
-    connect(ui->widget->xAxis, static_cast<void (QCPAxis::*)(const QCPRange &, const QCPRange &)>(
-                                   &QCPAxis::rangeChanged),
-            this, &VisualizationGraphWidget::onRangeChanged, Qt::DirectConnection);
+    connect(
+        ui->widget->xAxis,
+        static_cast<void (QCPAxis::*)(const QCPRange &, const QCPRange &)>(&QCPAxis::rangeChanged),
+        this, &VisualizationGraphWidget::onRangeChanged, Qt::DirectConnection);
 
     // Activates menu when right clicking on the graph
     ui->widget->setContextMenuPolicy(Qt::CustomContextMenu);
@@ -243,6 +244,16 @@ bool VisualizationGraphWidget::isDragAllowed() const
     return true;
 }
 
+void VisualizationGraphWidget::highlightForMerge(bool highlighted)
+{
+    if (highlighted) {
+        plot().setBackground(QBrush(QColor("#BBD5EE")));
+    }
+    else {
+        plot().setBackground(QBrush(Qt::white));
+    }
+}
+
 void VisualizationGraphWidget::closeEvent(QCloseEvent *event)
 {
     Q_UNUSED(event);
@@ -290,9 +301,9 @@ void VisualizationGraphWidget::onGraphMenuRequested(const QPoint &pos) noexcept
 
 void VisualizationGraphWidget::onRangeChanged(const QCPRange &t1, const QCPRange &t2)
 {
-    qCDebug(LOG_VisualizationGraphWidget()) << tr("TORM: VisualizationGraphWidget::onRangeChanged")
-                                            << QThread::currentThread()->objectName() << "DoAcqui"
-                                            << impl->m_DoAcquisition;
+    qCDebug(LOG_VisualizationGraphWidget())
+        << tr("TORM: VisualizationGraphWidget::onRangeChanged")
+        << QThread::currentThread()->objectName() << "DoAcqui" << impl->m_DoAcquisition;
 
     auto graphRange = SqpRange{t1.lower, t1.upper};
     auto oldGraphRange = SqpRange{t2.lower, t2.upper};