diff --git a/dgl/ntk/NtkApp.hpp b/dgl/ntk/NtkApp.hpp
index b45b3f66..20d9fdca 100644
--- a/dgl/ntk/NtkApp.hpp
+++ b/dgl/ntk/NtkApp.hpp
@@ -42,7 +42,7 @@ public:
       Constructor.
     */
     NtkApp()
-        : fIsRunning(false),
+        : fIsRunning(true),
           fWindows()
     {
         static bool initialized = false;
@@ -51,7 +51,9 @@ public:
         {
             initialized = true;
             fl_register_images();
+#ifdef DISTRHO_OS_LINUX
             fl_open_display();
+#endif
         }
     }
 
@@ -67,7 +69,7 @@ public:
 
    /**
       Idle function.
-      This calls the NTK event-loop once.
+      This calls the NTK event-loop once (and all idle callbacks).
     */
     void idle()
     {
@@ -115,6 +117,28 @@ private:
 
     friend class NtkWindow;
 
+   /** @internal used by NtkWindow. */
+    void addWindow(Fl_Double_Window* const window)
+    {
+        DISTRHO_SAFE_ASSERT_RETURN(window != nullptr,);
+
+        if (fWindows.size() == 0)
+            fIsRunning = true;
+
+        fWindows.push_back(window);
+    }
+
+   /** @internal used by NtkWindow. */
+    void removeWindow(Fl_Double_Window* const window)
+    {
+        DISTRHO_SAFE_ASSERT_RETURN(window != nullptr,);
+
+        fWindows.remove(window);
+
+        if (fWindows.size() == 0)
+            fIsRunning = false;
+    }
+
     DISTRHO_DECLARE_NON_COPYABLE_WITH_LEAK_DETECTOR(NtkApp)
 };
 
diff --git a/dgl/ntk/NtkWidget.hpp b/dgl/ntk/NtkWidget.hpp
index 91603fb8..b11e4e92 100644
--- a/dgl/ntk/NtkWidget.hpp
+++ b/dgl/ntk/NtkWidget.hpp
@@ -19,8 +19,6 @@
 
 #include "NtkWindow.hpp"
 
-#include "../Geometry.hpp"
-
 START_NAMESPACE_DGL
 
 // -----------------------------------------------------------------------
@@ -29,16 +27,18 @@ START_NAMESPACE_DGL
    DGL compatible Widget class that uses NTK instead of OpenGL.
    @see Widget
  */
-class NtkWidget : public Fl_Group
+class NtkWidget : public Fl_Double_Window
 {
 public:
    /**
       Constructor.
     */
     explicit NtkWidget(NtkWindow& parent)
-        : Fl_Group(0, 0, 0, 0),
+        : Fl_Double_Window(100, 100),
           fParent(parent)
     {
+        fParent.add(this);
+        show();
     }
 
    /**
@@ -46,6 +46,181 @@ public:
     */
     ~NtkWidget() override
     {
+        hide();
+        fParent.remove(this);
+    }
+
+   /**
+      Check if this widget is visible within its parent window.
+      Invisible widgets do not receive events except resize.
+    */
+    bool isVisible() const
+    {
+        return visible();
+    }
+
+   /**
+      Set widget visible (or not) according to @a yesNo.
+    */
+    void setVisible(bool yesNo)
+    {
+        if (yesNo)
+            show();
+        else
+            hide();
+    }
+
+   /**
+      Get width.
+    */
+    int getWidth() const
+    {
+        return w();
+    }
+
+   /**
+      Get height.
+    */
+    int getHeight() const
+    {
+        return h();
+    }
+
+   /**
+      Get size.
+    */
+    Size<int> getSize() const
+    {
+        return Size<int>(w(), h());
+    }
+
+   /**
+      Set width.
+    */
+    void setWidth(int width)
+    {
+        resize(x(), y(), width, h());
+    }
+
+   /**
+      Set height.
+    */
+    void setHeight(int height)
+    {
+        resize(x(), y(), w(), height);
+    }
+
+   /**
+      Set size using @a width and @a height values.
+    */
+    void setSize(int width, int height)
+    {
+        resize(x(), y(), width, height);
+    }
+
+   /**
+      Set size.
+    */
+    void setSize(const Size<int>& size)
+    {
+        resize(x(), y(), size.getWidth(), size.getHeight());
+    }
+
+   /**
+      Get absolute X.
+    */
+    int getAbsoluteX() const
+    {
+        return x();
+    }
+
+   /**
+      Get absolute Y.
+    */
+    int getAbsoluteY() const
+    {
+        return y();
+    }
+
+   /**
+      Get absolute position.
+    */
+    Point<int> getAbsolutePos() const
+    {
+        return Point<int>(x(), y());
+    }
+
+   /**
+      Set absolute X.
+    */
+    void setAbsoluteX(int x)
+    {
+        resize(x, y(), w(), h());
+    }
+
+   /**
+      Set absolute Y.
+    */
+    void setAbsoluteY(int y)
+    {
+        resize(x(), y, w(), h());
+    }
+
+   /**
+      Set absolute position using @a x and @a y values.
+    */
+    void setAbsolutePos(int x, int y)
+    {
+        resize(x, y, w(), h());
+    }
+
+   /**
+      Set absolute position.
+    */
+    void setAbsolutePos(const Point<int>& pos)
+    {
+        resize(pos.getX(), pos.getY(), w(), h());
+    }
+
+   /**
+      Get this widget's window application.
+      Same as calling getParentWindow().getApp().
+    */
+    NtkApp& getParentApp() const noexcept
+    {
+        return fParent.getApp();
+    }
+
+   /**
+      Get parent window, as passed in the constructor.
+    */
+    NtkWindow& getParentWindow() const noexcept
+    {
+        return fParent;
+    }
+
+   /**
+      Check if this widget contains the point defined by @a x and @a y.
+    */
+    bool contains(int x, int y) const
+    {
+        return (x >= 0 && y >= 0 && x < w() && y < h());
+    }
+
+   /**
+      Check if this widget contains the point @a pos.
+    */
+    bool contains(const Point<int>& pos) const
+    {
+        return contains(pos.getX(), pos.getY());
+    }
+
+   /**
+      Tell this widget's window to repaint itself.
+    */
+    void repaint()
+    {
+        redraw();
     }
 
 protected:
diff --git a/dgl/ntk/NtkWindow.hpp b/dgl/ntk/NtkWindow.hpp
index 7e4ad95f..81ad45b6 100644
--- a/dgl/ntk/NtkWindow.hpp
+++ b/dgl/ntk/NtkWindow.hpp
@@ -19,6 +19,8 @@
 
 #include "NtkApp.hpp"
 
+#include "../Geometry.hpp"
+
 START_NAMESPACE_DGL
 
 class NtkWidget;
@@ -31,59 +33,147 @@ public:
     explicit NtkWindow(NtkApp& app)
         : Fl_Double_Window(100, 100),
           fApp(app),
+          fIsVisible(false),
           fUsingEmbed(false),
-          fParent(nullptr),
-          fWidgets() {}
+          fParent(nullptr) {}
 
     explicit NtkWindow(NtkApp& app, NtkWindow& parent)
         : Fl_Double_Window(100, 100),
           fApp(app),
+          fIsVisible(false),
           fUsingEmbed(false),
-          fParent(&parent),
-          fWidgets() {}
+          fParent(&parent) {}
 
     explicit NtkWindow(NtkApp& app, intptr_t parentId)
         : Fl_Double_Window(100, 100),
           fApp(app),
+          fIsVisible(parentId != 0),
           fUsingEmbed(parentId != 0),
-          fParent(nullptr),
-          fWidgets()
+          fParent(nullptr)
     {
         if (fUsingEmbed)
         {
             fl_embed(this, (Window)parentId);
             Fl_Double_Window::show();
+            fApp.addWindow(this);
         }
     }
 
     ~NtkWindow() override
     {
-        fWidgets.clear();
-
         if (fUsingEmbed)
+        {
+            fApp.removeWindow(this);
             Fl_Double_Window::hide();
+        }
     }
 
-    void show()
+    void show() override
     {
+        if (fUsingEmbed || fIsVisible)
+            return;
+
         Fl_Double_Window::show();
+        fApp.addWindow(this);
+        fIsVisible = true;
 
-#ifdef DISTRHO_OS_LINUX
-        if (fParent == nullptr)
+        if (fParent != nullptr)
+            setTransientWinId((intptr_t)fl_xid(fParent));
+    }
+
+    void hide() override
+    {
+        if (fUsingEmbed || ! fIsVisible)
             return;
 
+        fIsVisible = false;
+        fApp.removeWindow(this);
+        Fl_Double_Window::hide();
+    }
+
+    void close()
+    {
+        hide();
+    }
+
+    bool isVisible() const
+    {
+        return visible();
+    }
+
+    void setVisible(bool yesNo)
+    {
+        if (yesNo)
+            show();
+        else
+            hide();
+    }
+
+    bool isResizable() const
+    {
+        // TODO
+        return false;
+    }
+
+    void setResizable(bool /*yesNo*/)
+    {
+        // TODO
+    }
+
+    int getWidth() const noexcept
+    {
+        return w();
+    }
+
+    int getHeight() const noexcept
+    {
+        return h();
+    }
+
+    Size<uint> getSize() const noexcept
+    {
+        return Size<uint>(w(), h());
+    }
+
+    void setSize(uint width, uint height)
+    {
+        resize(x(), y(), width, height);
+    }
+
+    void setSize(Size<uint> size)
+    {
+        resize(x(), y(), size.getWidth(), size.getHeight());
+    }
+
+    void setTitle(const char* title)
+    {
+        label(title);
+    }
+
+    void setTransientWinId(intptr_t winId)
+    {
+        DISTRHO_SAFE_ASSERT_RETURN(winId != 0,);
+
+#ifdef DISTRHO_OS_LINUX
         DISTRHO_SAFE_ASSERT_RETURN(fl_display != nullptr,);
 
-        const ::Window ourWindow(fl_xid_(this));
+        const ::Window ourWindow(fl_xid(this));
         DISTRHO_SAFE_ASSERT_RETURN(ourWindow != 0,);
 
-        const ::Window parentWindow(fl_xid_(fParent));
-        DISTRHO_SAFE_ASSERT_RETURN(parentWindow != 0,);
-
-        XSetTransientForHint(fl_display, ourWindow, parentWindow);
+        XSetTransientForHint(fl_display, ourWindow, winId);
 #endif
     }
 
+    NtkApp& getApp() const noexcept
+    {
+        return fApp;
+    }
+
+    intptr_t getWindowId() const
+    {
+        return (intptr_t)fl_xid(this);
+    }
+
     void addIdleCallback(IdleCallback* const callback)
     {
         DISTRHO_SAFE_ASSERT_RETURN(callback != nullptr,);
@@ -106,12 +196,12 @@ public:
 
 private:
     NtkApp& fApp;
+    bool    fIsVisible;
     bool    fUsingEmbed;
 
     // transient parent, may be null
     NtkWindow* const fParent;
 
-    std::list<Fl_Group*> fWidgets;
     std::list<IdleCallback*> fIdleCallbacks;
 
     friend class NtkWidget;
diff --git a/distrho/DistrhoUI.hpp b/distrho/DistrhoUI.hpp
index 3901067d..7c34f0a0 100644
--- a/distrho/DistrhoUI.hpp
+++ b/distrho/DistrhoUI.hpp
@@ -95,7 +95,11 @@ protected:
     // UI Callbacks (optional)
 
     virtual void d_uiIdle() {}
+
+#if ! DISTRHO_UI_USE_NTK
+    // updates window openGL state
     virtual void d_uiReshape(int width, int height);
+#endif
 
     // -------------------------------------------------------------------
 
@@ -106,6 +110,7 @@ private:
     friend class UIExporterWindow;
 
     // these should not be used
+    void position(int, int) noexcept {}
     void setAbsoluteX(int) const noexcept {}
     void setAbsoluteY(int) const noexcept {}
     void setAbsolutePos(int, int) const noexcept {}
diff --git a/distrho/src/DistrhoUI.cpp b/distrho/src/DistrhoUI.cpp
index 7d2951ff..1295dc7d 100644
--- a/distrho/src/DistrhoUI.cpp
+++ b/distrho/src/DistrhoUI.cpp
@@ -98,9 +98,9 @@ void UI::d_sampleRateChanged(double) {}
 // -----------------------------------------------------------------------
 // UI Callbacks (optional)
 
+#if ! DISTRHO_UI_USE_NTK
 void UI::d_uiReshape(int width, int height)
 {
-#if ! DISTRHO_UI_USE_NTK
     glEnable(GL_BLEND);
     glBlendFunc(GL_SRC_ALPHA, GL_ONE_MINUS_SRC_ALPHA);
     glMatrixMode(GL_PROJECTION);
@@ -109,10 +109,8 @@ void UI::d_uiReshape(int width, int height)
     glViewport(0, 0, width, height);
     glMatrixMode(GL_MODELVIEW);
     glLoadIdentity();
-#else
-    (void)width; (void)height;
-#endif
 }
+#endif
 
 // -----------------------------------------------------------------------
 
diff --git a/distrho/src/DistrhoUIInternal.hpp b/distrho/src/DistrhoUIInternal.hpp
index 1eaca647..dd114918 100644
--- a/distrho/src/DistrhoUIInternal.hpp
+++ b/distrho/src/DistrhoUIInternal.hpp
@@ -157,17 +157,15 @@ public:
     {
         DISTRHO_SAFE_ASSERT_RETURN(fUI != nullptr,);
 
-#if ! DISTRHO_UI_USE_NTK
         const int width  = fUI->d_getWidth();
         const int height = fUI->d_getHeight();
 
         // set widget size
         fUI->setSize(width, height);
 
-        // set this window size
+        // set window size
         setResizable(false);
         setSize(width, height);
-#endif
     }
 
     ~UIExporterWindow()
@@ -185,8 +183,14 @@ public:
         return fIsReady;
     }
 
-#if ! DISTRHO_UI_USE_NTK
 protected:
+#if DISTRHO_UI_USE_NTK
+    void resize(int x, int y, int width, int height) override
+    {
+        UIWindow::resize(x, y, width, height);
+        fIsReady = true;
+    }
+#else
     void onReshape(int width, int height) override
     {
         DISTRHO_SAFE_ASSERT_RETURN(fUI != nullptr,);
@@ -292,7 +296,6 @@ public:
     }
 #endif
 
-#if ! DISTRHO_UI_USE_NTK
     // -------------------------------------------------------------------
 
     void exec(IdleCallback* const cb)
@@ -355,7 +358,6 @@ public:
 
         return ! glApp.isQuiting();
     }
-#endif
 
     void setSampleRate(const double sampleRate, const bool doCallback = false)
     {