diff --git a/source/libs/distrho/DistrhoUIMain.cpp b/source/libs/distrho/DistrhoUIMain.cpp
index 7193abbed..945a9b21e 100644
--- a/source/libs/distrho/DistrhoUIMain.cpp
+++ b/source/libs/distrho/DistrhoUIMain.cpp
@@ -26,8 +26,10 @@
 // nothing
 #endif
 
-#ifdef DISTRHO_UI_QT
-# include "src/DistrhoUIQt.cpp"
-#else
+#if defined(DISTRHO_UI_EXTERNAL)
+# include "src/DistrhoUIExternal.cpp"
+#elif defined(DISTRHO_UI_OPENGL)
 # include "src/DistrhoUIOpenGL.cpp"
+#else
+# include "src/DistrhoUIQt.cpp"
 #endif
diff --git a/source/libs/distrho/DistrhoUIOpenGL.hpp b/source/libs/distrho/DistrhoUIOpenGL.hpp
index e0f95df65..de6cf6175 100644
--- a/source/libs/distrho/DistrhoUIOpenGL.hpp
+++ b/source/libs/distrho/DistrhoUIOpenGL.hpp
@@ -33,33 +33,33 @@ class OpenGLUI : public UI,
 {
 public:
     OpenGLUI();
-    virtual ~OpenGLUI();
+    virtual ~OpenGLUI() override;
 
 protected:
     // ---------------------------------------------
     // Information
 
-    virtual unsigned int d_width() const = 0;
-    virtual unsigned int d_height() const = 0;
+    virtual unsigned int d_width() const override = 0;
+    virtual unsigned int d_height() const override = 0;
 
     // ---------------------------------------------
     // DSP Callbacks
 
-    virtual void d_parameterChanged(uint32_t index, float value) = 0;
+    virtual void d_parameterChanged(uint32_t index, float value) override = 0;
 #if DISTRHO_PLUGIN_WANT_PROGRAMS
-    virtual void d_programChanged(uint32_t index) = 0;
+    virtual void d_programChanged(uint32_t index) override = 0;
 #endif
 #if DISTRHO_PLUGIN_WANT_STATE
-    virtual void d_stateChanged(const char* key, const char* value) = 0;
+    virtual void d_stateChanged(const char* key, const char* value) override = 0;
 #endif
 #if DISTRHO_PLUGIN_IS_SYNTH
-    virtual void d_noteReceived(bool onOff, uint8_t channel, uint8_t note, uint8_t velocity) = 0;
+    virtual void d_noteReceived(bool onOff, uint8_t channel, uint8_t note, uint8_t velocity) override = 0;
 #endif
 
     // ---------------------------------------------
     // UI Callbacks
 
-    virtual void d_uiIdle() {}
+    virtual void d_uiIdle() override {}
 
 private:
     friend class UIInternal;
diff --git a/source/libs/distrho/DistrhoUIQt.hpp b/source/libs/distrho/DistrhoUIQt.hpp
index 58ab8932c..685da7327 100644
--- a/source/libs/distrho/DistrhoUIQt.hpp
+++ b/source/libs/distrho/DistrhoUIQt.hpp
@@ -37,7 +37,12 @@ class QtUI : public UI,
 {
 public:
     QtUI();
-    virtual ~QtUI();
+    virtual ~QtUI() override;
+
+    // ---------------------------------------------
+    // UI Helpers
+
+    void setSize(unsigned int width, unsigned int height);
 
 protected:
     // ---------------------------------------------
@@ -50,32 +55,27 @@ protected:
     // ---------------------------------------------
     // DSP Callbacks
 
-    virtual void d_parameterChanged(uint32_t index, float value) = 0;
+    virtual void d_parameterChanged(uint32_t index, float value) override = 0;
 #if DISTRHO_PLUGIN_WANT_PROGRAMS
-    virtual void d_programChanged(uint32_t index) = 0;
+    virtual void d_programChanged(uint32_t index) override = 0;
 #endif
 #if DISTRHO_PLUGIN_WANT_STATE
-    virtual void d_stateChanged(const char* key, const char* value) = 0;
+    virtual void d_stateChanged(const char* key, const char* value) override = 0;
 #endif
 #if DISTRHO_PLUGIN_IS_SYNTH
-    virtual void d_noteReceived(bool onOff, uint8_t channel, uint8_t note, uint8_t velocity) = 0;
+    virtual void d_noteReceived(bool onOff, uint8_t channel, uint8_t note, uint8_t velocity) override = 0;
 #endif
 
     // ---------------------------------------------
     // UI Callbacks
 
-    virtual void d_uiIdle() {}
-
-    // ---------------------------------------------
-    // UI Helpers
-
-    void setSize(unsigned int width, unsigned int height);
+    virtual void d_uiIdle() override {}
 
 private:
     friend class UIInternal;
 
-    unsigned int d_width() const { return width(); }
-    unsigned int d_height() const { return height(); }
+    unsigned int d_width() const override { return width(); }
+    unsigned int d_height() const override { return height(); }
 };
 
 // -------------------------------------------------
diff --git a/source/libs/distrho/src/DistrhoUIOpenGL.cpp b/source/libs/distrho/src/DistrhoUIOpenGL.cpp
index cb6506711..e1f04d2c4 100644
--- a/source/libs/distrho/src/DistrhoUIOpenGL.cpp
+++ b/source/libs/distrho/src/DistrhoUIOpenGL.cpp
@@ -23,7 +23,7 @@ END_NAMESPACE_DGL
 START_NAMESPACE_DISTRHO
 
 // -------------------------------------------------
-// OpenGLUI
+// OpenGL UI
 
 OpenGLUI::OpenGLUI()
     : UI(),
diff --git a/source/libs/distrho/src/DistrhoUIQt.cpp b/source/libs/distrho/src/DistrhoUIQt.cpp
index 1402ec469..d6a6ff0f6 100644
--- a/source/libs/distrho/src/DistrhoUIQt.cpp
+++ b/source/libs/distrho/src/DistrhoUIQt.cpp
@@ -21,7 +21,7 @@
 START_NAMESPACE_DISTRHO
 
 // -------------------------------------------------
-// Qt4UI
+// Qt UI
 
 QtUI::QtUI()
     : UI(),
@@ -33,6 +33,8 @@ QtUI::~QtUI()
 {
 }
 
+// -------------------------------------------------
+
 void QtUI::setSize(unsigned int width, unsigned int height)
 {
     if (d_resizable())