feat: implement type-safe ReferenceProperty for SmartPointer fields and add UI support for object selection via context-aware dropdowns

app/gcompose/src/ContextPanel.cpp

@@ -90,6 +90,10 @@ void ContextPanel::setContext(uLib::ObjectsContext* context) {
     m_treeView->expandAll();
 }
 
+void ContextPanel::setPropertyContext(uLib::ObjectsContext* context) {
+    m_propertiesPanel->setContext(context);
+}
+
 void ContextPanel::onSelectionChanged(const QItemSelection& selected, const QItemSelection& deselected) {
     uLib::Object* target = nullptr;
     if (!selected.indexes().isEmpty()) {

app/gcompose/src/ContextPanel.h

@@ -20,6 +20,7 @@ public:
     ~ContextPanel();
 
     void setContext(uLib::ObjectsContext* context);
+    void setPropertyContext(uLib::ObjectsContext* context);
     void selectObject(uLib::Object* obj);
     void clearSelection();
 

app/gcompose/src/MainPanel.cpp

@@ -127,7 +127,10 @@ MainPanel::MainPanel(QWidget* parent) : QWidget(parent), m_context(nullptr), m_m
 void MainPanel::setContext(uLib::ObjectsContext* context) {
     m_context = context;
     m_contextPanel->setContext(context);
-
+    
+    // Propagate context to all panels for reference property dropdowns
+    m_contextPanel->setPropertyContext(context);
+    m_firstPane->setContext(context);
     if (m_mainVtkContext) {
         if (auto* viewport = qobject_cast<uLib::Vtk::QViewport*>(m_firstPane->currentViewport())) {
             viewport->RemoveProp3D(*m_mainVtkContext);

app/gcompose/src/PropertiesPanel.cpp

@@ -47,4 +47,8 @@ void PropertiesPanel::setObject(uLib::Object* obj) {
     m_editor->setObject(obj);
 }
 
+void PropertiesPanel::setContext(uLib::ObjectsContext* context) {
+    m_editor->setContext(context);
+}
+
 PropertiesPanel::~PropertiesPanel() {}

app/gcompose/src/PropertiesPanel.h

@@ -5,6 +5,7 @@
 
 namespace uLib {
     class Object;
+    class ObjectsContext;
     namespace Qt { class PropertyEditor; }
 }
 
@@ -23,6 +24,9 @@ public:
 
     /** @brief Sets the object to be inspected. */
     void setObject(uLib::Object* obj);
+    
+    /** @brief Sets the context for reference property dropdowns. */
+    void setContext(uLib::ObjectsContext* context);
 
 signals:
     void propertyUpdated();

app/gcompose/src/PropertyWidgets.cpp

@@ -13,6 +13,7 @@
 #include <QSlider>
 #include <QFontDialog>
 #include "Settings.h"
+#include "Core/ObjectsContext.h"
 
 namespace uLib {
 namespace Qt {
@@ -386,7 +387,74 @@ public:
     }
 };
 
-PropertyEditor::PropertyEditor(QWidget* parent) : QWidget(parent), m_Object(nullptr) {
+////////////////////////////////////////////////////////////////////////////////
+// ReferencePropertyWidget
+
+ReferencePropertyWidget::ReferencePropertyWidget(ReferencePropertyBase* prop, ::uLib::ObjectsContext* context, QWidget* parent)
+    : PropertyWidgetBase(prop, parent), m_RefProp(prop), m_Context(context) {
+    m_Combo = new QComboBox(static_cast<QWidget*>(this));
+    m_Layout->addWidget(m_Combo, 1);
+    refreshCombo();
+    connect(m_Combo, &QComboBox::currentIndexChanged, this, &ReferencePropertyWidget::onComboChanged);
+
+    // Listen for property updates to refresh selected item
+    m_Connection = uLib::Object::connect(prop, &uLib::Object::Updated, [this](){
+        QSignalBlocker blocker(m_Combo);
+        refreshCombo();
+    });
+
+    // Listen for context changes to refresh the dropdown list
+    if (m_Context) {
+        m_ContextConnection = uLib::Object::connect(m_Context, &uLib::Object::Updated, [this](){
+            QSignalBlocker blocker(m_Combo);
+            refreshCombo();
+        });
+    }
+}
+
+ReferencePropertyWidget::~ReferencePropertyWidget() {
+    m_Connection.disconnect();
+    m_ContextConnection.disconnect();
+}
+
+void ReferencePropertyWidget::refreshCombo() {
+    m_Combo->clear();
+    m_Combo->addItem("(none)", QVariant::fromValue((quintptr)0));
+
+    int selectedIdx = 0;
+    Object* currentRef = m_RefProp->GetReferencedObject();
+
+    if (m_Context) {
+        const auto& objects = m_Context->GetObjects();
+        for (auto* obj : objects) {
+            if (m_RefProp->IsCompatible(obj)) {
+                QString label = QString::fromStdString(obj->GetInstanceName());
+                if (label.isEmpty()) {
+                    label = QString::fromStdString(std::string(obj->GetClassName()));
+                }
+                // Add index suffix if name is empty to disambiguate
+                m_Combo->addItem(label, QVariant::fromValue((quintptr)obj));
+                if (obj == currentRef) {
+                    selectedIdx = m_Combo->count() - 1;
+                }
+            }
+        }
+    }
+    m_Combo->setCurrentIndex(selectedIdx);
+}
+
+void ReferencePropertyWidget::onComboChanged(int index) {
+    if (index < 0) return;
+    quintptr ptr = m_Combo->itemData(index).value<quintptr>();
+    Object* obj = reinterpret_cast<Object*>(ptr);
+    m_RefProp->SetReferencedObject(obj);
+    Q_EMIT updated();
+}
+
+////////////////////////////////////////////////////////////////////////////////
+// PropertyEditor
+
+PropertyEditor::PropertyEditor(QWidget* parent) : QWidget(parent), m_Object(nullptr), m_Context(nullptr) {
     m_MainLayout = new QVBoxLayout(this);
     m_MainLayout->setContentsMargins(0, 0, 0, 0);
     m_ScrollArea = new QScrollArea(this);
@@ -488,18 +556,23 @@ void PropertyEditor::setObject(::uLib::Object* obj, bool displayOnly) {
                      // widget = new RangePropertyWidget<float>(pflt, m_Container);
                 }
             } else {
-                // Priority 2: Standard factory lookup
+                // Priority 2: Check for reference properties (SmartPointer<T>)
+                if (auto* refProp = dynamic_cast<::uLib::ReferencePropertyBase*>(prop)) {
+                    widget = static_cast<QWidget*>(new ReferencePropertyWidget(refProp, m_Context, m_Container));
+                } else {
+                    // Priority 3: Standard factory lookup
                     auto it = m_Factories.find(prop->GetTypeIndex());
                     if (it != m_Factories.end()) {
                         widget = it->second(prop, m_Container);
                     } else {
-                    // Debug info for unknown types
-                    std::cout << "PropertyEditor: No factory for " << prop->GetQualifiedName() 
-                              << " (Type: " << prop->GetTypeName() << ")" << std::endl;
+                        // Debug info for unknown types
+                        std::cout << "PropertyEditor: No factory for " << prop->GetQualifiedName() 
+                                  << " (Type: " << prop->GetTypeName() << ")" << std::endl;
 
                         widget = new PropertyWidgetBase(prop, m_Container);
-                    widget->layout()->addWidget(new QLabel("(Read-only: " + QString::fromStdString(prop->GetValueAsString()) + ")"));
+                        widget->layout()->addWidget(new QLabel("(Read-only: " + QString::fromStdString(prop->GetValueAsString()) + ")"));
                     }
+                }
             }
 
             if (widget) {

app/gcompose/src/PropertyWidgets.h

@@ -4,6 +4,7 @@
 #include <QWidget>
 class QPushButton;
 class QSlider;
+class QComboBox;
 #include <QLabel>
 #include <QHBoxLayout>
 #include <QVBoxLayout>
@@ -21,6 +22,8 @@ class QSlider;
 #include "Math/Dense.h"
 #include "Settings.h"
 
+namespace uLib { class ObjectsContext; }
+
 namespace uLib {
 namespace Qt {
 
@@ -211,12 +214,28 @@ private:
     QPushButton* m_Button;
 };
 
+class ReferencePropertyWidget : public PropertyWidgetBase {
+    Q_OBJECT
+public:
+    ReferencePropertyWidget(ReferencePropertyBase* prop, ::uLib::ObjectsContext* context, QWidget* parent = nullptr);
+    virtual ~ReferencePropertyWidget();
+private slots:
+    void onComboChanged(int index);
+private:
+    void refreshCombo();
+    ReferencePropertyBase* m_RefProp;
+    ::uLib::ObjectsContext* m_Context;
+    QComboBox* m_Combo;
+    Connection m_ContextConnection;
+};
+
 class PropertyEditor : public QWidget {
     Q_OBJECT
 public:
     PropertyEditor(QWidget* parent = nullptr);
     virtual ~PropertyEditor();
     void setObject(uLib::Object* obj, bool displayOnly = false);
+    void setContext(uLib::ObjectsContext* context) { m_Context = context; }
     template<typename T>
     void registerFactory(std::function<QWidget*(PropertyBase*, QWidget*)> factory) {
         m_Factories[std::type_index(typeid(T))] = factory;
@@ -228,6 +247,7 @@ signals:
 private:
     void clear();
     uLib::Object* m_Object;
+    uLib::ObjectsContext* m_Context;
     QVBoxLayout* m_MainLayout;
     QScrollArea* m_ScrollArea;
     QWidget* m_Container;

app/gcompose/src/ViewportPane.cpp

@@ -113,6 +113,10 @@ void ViewportPane::setObject(uLib::Object* obj) {
     }
 }
 
+void ViewportPane::setContext(uLib::ObjectsContext* context) {
+    m_displayEditor->setContext(context);
+}
+
 void ViewportPane::setViewport(QWidget* viewport, const QString& title) {
     if (m_viewport) {
         delete m_viewport;

app/gcompose/src/ViewportPane.h

@@ -7,6 +7,7 @@
 
 namespace uLib {
     class Object;
+    class ObjectsContext;
     namespace Qt { class PropertyEditor; }
     namespace Vtk { class Viewport; }
 }
@@ -29,6 +30,9 @@ public:
     
     /** @brief Update the display properties for the given object. */
     void setObject(uLib::Object* obj);
+    
+    /** @brief Sets the context for reference property dropdowns. */
+    void setContext(uLib::ObjectsContext* context);
 
 private slots:
     void onCloseRequested();