diff --git a/dgl/SubWidget.hpp b/dgl/SubWidget.hpp
index 81c8ad59..45778703 100644
--- a/dgl/SubWidget.hpp
+++ b/dgl/SubWidget.hpp
@@ -23,6 +23,15 @@ START_NAMESPACE_DGL
 
 // -----------------------------------------------------------------------
 
+/**
+   Sub-Widget class.
+
+   This is a handy Widget class that can be freely positioned to be used directly on a Window.
+
+   This widget takes the full size of the Window it is mapped to.
+   Sub-widgets can be added on top of this top-level widget, by creating them with this class as parent.
+   Doing so allows for custom position and sizes.
+ */
 class SubWidget : public Widget
 {
 public:
diff --git a/dgl/TopLevelWidget.hpp b/dgl/TopLevelWidget.hpp
index 5b3fdb5f..056cbac8 100644
--- a/dgl/TopLevelWidget.hpp
+++ b/dgl/TopLevelWidget.hpp
@@ -35,8 +35,16 @@ START_NAMESPACE_DGL
 class TopLevelWidget : public Widget
 {
 public:
+   /**
+      Constructor.
+    */
     explicit TopLevelWidget(Window& windowToMapTo);
 
+   /**
+      Destructor.
+    */
+    virtual ~TopLevelWidget();
+
 private:
     struct PrivateData;
     PrivateData* const pData;
diff --git a/dgl/src/SubWidget.cpp b/dgl/src/SubWidget.cpp
index b987c518..f7934d75 100644
--- a/dgl/src/SubWidget.cpp
+++ b/dgl/src/SubWidget.cpp
@@ -16,6 +16,14 @@
 
 #include "SubWidgetPrivateData.hpp"
 
+SubWidget::SubWidget(Widget* const widgetToGroupTo)
+    : pData(new PrivateData(this, widgetToGroupTo)) {}
+
+SubWidget::~SubWidget()
+{
+    delete pData;
+}
+
 template<typename T>
 bool SubWidget::contains(T x, T y) const noexcept
 {
diff --git a/dgl/src/TopLevelWidget.cpp b/dgl/src/TopLevelWidget.cpp
index 782bd6af..903ccdca 100644
--- a/dgl/src/TopLevelWidget.cpp
+++ b/dgl/src/TopLevelWidget.cpp
@@ -15,3 +15,11 @@
  */
 
 #include "TopLevelWidgetPrivateData.hpp"
+
+TopLevelWidget::TopLevelWidget(Window& windowToMapTo)
+    : pData(new PrivateData(this, windowToMapTo)) {}
+
+TopLevelWidget::~TopLevelWidget()
+{
+    delete pData;
+}