diff --git a/source/backend/CarlaBackend.hpp b/source/backend/CarlaBackend.hpp
index 9615bbdba..e9acc58aa 100644
--- a/source/backend/CarlaBackend.hpp
+++ b/source/backend/CarlaBackend.hpp
@@ -722,7 +722,7 @@ struct ParameterRanges {
 
         if (newValue < 0.0f)
             newValue = 0.0f;
-        else if (newValue < 1.0f)
+        else if (newValue > 1.0f)
             newValue = 1.0f;
 
         return newValue;
diff --git a/source/backend/CarlaEngine.hpp b/source/backend/CarlaEngine.hpp
index 7197b7512..749aa2ab8 100644
--- a/source/backend/CarlaEngine.hpp
+++ b/source/backend/CarlaEngine.hpp
@@ -338,7 +338,7 @@ struct EngineTimeInfo {
     static const uint32_t ValidBBT = 0x1;
 
     bool playing;
-    uint32_t frame;
+    uint64_t frame;
     uint64_t usecs;
     uint32_t valid;
     EngineTimeInfoBBT bbt;
diff --git a/source/backend/CarlaNative.h b/source/backend/CarlaNative.h
index ae6f774e4..68c0b29f8 100644
--- a/source/backend/CarlaNative.h
+++ b/source/backend/CarlaNative.h
@@ -142,8 +142,8 @@ typedef struct _TimeInfoBBT {
 
 typedef struct _TimeInfo {
     bool playing;
-    uint32_t frame;
-    uint32_t usecs;
+    uint64_t frame;
+    uint64_t usecs;
     TimeInfoBBT bbt;
 } TimeInfo;
 
diff --git a/source/backend/engine/CarlaEnginePlugin.cpp b/source/backend/engine/CarlaEnginePlugin.cpp
index e321cb680..cef62be4f 100644
--- a/source/backend/engine/CarlaEnginePlugin.cpp
+++ b/source/backend/engine/CarlaEnginePlugin.cpp
@@ -23,6 +23,9 @@
 using DISTRHO::d_cconst;
 using DISTRHO::d_string;
 
+#ifdef QTCREATOR_TEST
+CARLA_BACKEND_START_NAMESPACE
+#else
 // -----------------------------------------
 // needed symbols
 
@@ -33,11 +36,12 @@ CARLA_BACKEND_START_NAMESPACE
 
 CarlaEngine* CarlaEngine::newJack() { return nullptr; }
 
-#ifdef WANT_RTAUDIO
+# ifdef WANT_RTAUDIO
 CarlaEngine* CarlaEngine::newRtAudio(RtAudioApi) { return nullptr; }
 size_t       CarlaEngine::getRtAudioApiCount()   { return 0; }
 const char*  CarlaEngine::getRtAudioApiName(const unsigned int)        { return nullptr; }
 const char** CarlaEngine::getRtAudioApiDeviceNames(const unsigned int) { return nullptr; }
+# endif
 #endif
 
 // -----------------------------------------
diff --git a/source/backend/engine/distrho/DistrhoPluginInfo.h b/source/backend/engine/distrho/DistrhoPluginInfo.h
index bb2634eb3..2596a5725 100644
--- a/source/backend/engine/distrho/DistrhoPluginInfo.h
+++ b/source/backend/engine/distrho/DistrhoPluginInfo.h
@@ -1,5 +1,5 @@
 /*
- * Carla Plugin Engine
+ * Carla Plugin Engine (DISTRHO)
  * Copyright (C) 2012-2013 Filipe Coelho <falktx@falktx.com>
  *
  * This program is free software; you can redistribute it and/or
@@ -20,16 +20,18 @@
 
 #define DISTRHO_PLUGIN_NAME "Carla"
 
-#define DISTRHO_PLUGIN_HAS_UI        0
+#define DISTRHO_PLUGIN_HAS_UI        1
 #define DISTRHO_PLUGIN_IS_SYNTH      1
 
 #define DISTRHO_PLUGIN_NUM_INPUTS    2
 #define DISTRHO_PLUGIN_NUM_OUTPUTS   2
 
-#define DISTRHO_PLUGIN_WANT_LATENCY  1
+#define DISTRHO_PLUGIN_WANT_LATENCY  0
 #define DISTRHO_PLUGIN_WANT_PROGRAMS 1
 #define DISTRHO_PLUGIN_WANT_STATE    1
 
 #define DISTRHO_PLUGIN_URI "http://kxstudio.sf.net/carla"
 
+#define DISTRHO_UI_EXTERNAL
+
 #endif // __DISTRHO_PLUGIN_INFO_H__
diff --git a/source/backend/native/3bandeq/DistrhoPluginInfo.h b/source/backend/native/3bandeq/DistrhoPluginInfo.h
index cb17c9351..f8b9afba1 100644
--- a/source/backend/native/3bandeq/DistrhoPluginInfo.h
+++ b/source/backend/native/3bandeq/DistrhoPluginInfo.h
@@ -31,4 +31,6 @@
 
 #define DISTRHO_PLUGIN_URI "http://distrho.sf.net/plugins/3BandEQ"
 
+#define DISTRHO_UI_OPENGL
+
 #endif // __DISTRHO_PLUGIN_INFO_H__
diff --git a/source/backend/native/3bandsplitter/DistrhoPluginInfo.h b/source/backend/native/3bandsplitter/DistrhoPluginInfo.h
index 41840f799..22004ec17 100644
--- a/source/backend/native/3bandsplitter/DistrhoPluginInfo.h
+++ b/source/backend/native/3bandsplitter/DistrhoPluginInfo.h
@@ -31,4 +31,6 @@
 
 #define DISTRHO_PLUGIN_URI "http://distrho.sf.net/plugins/3BandSplitter"
 
+#define DISTRHO_UI_OPENGL
+
 #endif // __DISTRHO_PLUGIN_INFO_H__
diff --git a/source/backend/native/pingpongpan/DistrhoPluginInfo.h b/source/backend/native/pingpongpan/DistrhoPluginInfo.h
index fd1332005..5306dfa4f 100644
--- a/source/backend/native/pingpongpan/DistrhoPluginInfo.h
+++ b/source/backend/native/pingpongpan/DistrhoPluginInfo.h
@@ -31,4 +31,6 @@
 
 #define DISTRHO_PLUGIN_URI "http://distrho.sf.net/plugins/PingPongPan"
 
+#define DISTRHO_UI_OPENGL
+
 #endif // __DISTRHO_PLUGIN_INFO_H__
diff --git a/source/libs/distrho/DistrhoPlugin.hpp b/source/libs/distrho/DistrhoPlugin.hpp
index 1101eb4fe..a7eef7ea1 100644
--- a/source/libs/distrho/DistrhoPlugin.hpp
+++ b/source/libs/distrho/DistrhoPlugin.hpp
@@ -79,9 +79,25 @@ struct ParameterRanges {
             value = max;
     }
 
+    float fixValue(const float& value) const
+    {
+        if (value < min)
+            return min;
+        else if (value > max)
+            return max;
+        return value;
+    }
+
     float normalizeValue(const float& value) const
     {
-        return (value - min) / (max - min);
+        float newValue = (value - min) / (max - min);
+
+        if (newValue < 0.0f)
+            newValue = 0.0f;
+        else if (newValue > 1.0f)
+            newValue = 1.0f;
+
+        return newValue;
     }
 
     float unnormalizeValue(const float& value) const
@@ -132,17 +148,19 @@ struct MidiEvent {
 // TimePos
 
 struct TimePos {
+    bool playing;
+    uint64_t frame;
     double bpm;
 
     TimePos()
-        : bpm(120.0) {}
+        : playing(false),
+          frame(0),
+          bpm(120.0) {}
 };
 
 // -------------------------------------------------
 // Plugin
 
-struct PluginPrivateData;
-
 class Plugin
 {
 public:
@@ -209,7 +227,8 @@ protected:
     // ---------------------------------------------
 
 private:
-    PluginPrivateData* const pData;
+    struct PrivateData;
+    PrivateData* const pData;
     friend class PluginInternal;
 };
 
diff --git a/source/libs/distrho/DistrhoUI.hpp b/source/libs/distrho/DistrhoUI.hpp
index 55902df7c..1378eec8e 100644
--- a/source/libs/distrho/DistrhoUI.hpp
+++ b/source/libs/distrho/DistrhoUI.hpp
@@ -26,8 +26,6 @@ START_NAMESPACE_DISTRHO
 // -------------------------------------------------
 // UI
 
-struct UIPrivateData;
-
 class UI
 {
 public:
@@ -82,7 +80,8 @@ protected:
     // ---------------------------------------------
 
 private:
-    UIPrivateData* const pData;
+    struct PrivateData;
+    PrivateData* const pData;
     friend class UIInternal;
 };
 
diff --git a/source/libs/distrho/DistrhoUtils.hpp b/source/libs/distrho/DistrhoUtils.hpp
index bb1460760..7f283f7ee 100644
--- a/source/libs/distrho/DistrhoUtils.hpp
+++ b/source/libs/distrho/DistrhoUtils.hpp
@@ -62,16 +62,6 @@ void d_msleep(unsigned int msecs)
 #endif
 }
 
-static inline
-void d_usleep(unsigned int usecs)
-{
-#ifdef DISTRHO_OS_WINDOWS
-    Sleep(usecs / 1000);
-#else
-    usleep(usecs);
-#endif
-}
-
 // -------------------------------------------------
 
 static inline
@@ -504,4 +494,4 @@ d_string operator+(const char* const strBufBefore, const d_string& strAfter)
 
 END_NAMESPACE_DISTRHO
 
-#endif // __UTILS_HPP__
+#endif // __DISTRHO_UTILS_HPP__
diff --git a/source/libs/distrho/src/DistrhoDefines.h b/source/libs/distrho/src/DistrhoDefines.h
index f82f15452..96a485b9f 100644
--- a/source/libs/distrho/src/DistrhoDefines.h
+++ b/source/libs/distrho/src/DistrhoDefines.h
@@ -51,6 +51,12 @@
 # error DISTRHO_PLUGIN_WANT_STATE undefined!
 #endif
 
+#if DISTRHO_PLUGIN_HAS_UI
+# if ! (defined(DISTRHO_UI_EXTERNAL) || defined(DISTRHO_UI_OPENGL) || defined(DISTRHO_UI_QT))
+#  error DISTRHO_PLUGIN_HAS_UI is defined but not its type; please define one of DISTRHO_UI_EXTERNAL, DISTRHO_UI_OPENGL or DISTRHO_UI_QT
+# endif
+#endif
+
 #if defined(WIN32) || defined(_WIN32) || defined(__WIN32__)
 # define DISTRHO_PLUGIN_EXPORT extern "C" __declspec (dllexport)
 # define DISTRHO_OS_WINDOWS    1
@@ -86,10 +92,6 @@
 # define USE_NAMESPACE_DISTRHO
 #endif
 
-#ifndef DISTRHO_UI_QT
-# define DISTRHO_UI_OPENGL
-#endif
-
 #define DISTRHO_UI_URI DISTRHO_PLUGIN_URI "#UI"
 
 #endif // __DISTRHO_DEFINES_H__
diff --git a/source/libs/distrho/src/DistrhoPlugin.cpp b/source/libs/distrho/src/DistrhoPlugin.cpp
index 976493671..80ea640a3 100644
--- a/source/libs/distrho/src/DistrhoPlugin.cpp
+++ b/source/libs/distrho/src/DistrhoPlugin.cpp
@@ -34,7 +34,7 @@ const ParameterRanges PluginInternal::sFallbackRanges;
 // Plugin
 
 Plugin::Plugin(uint32_t parameterCount, uint32_t programCount, uint32_t stateCount)
-    : pData(new PluginPrivateData)
+    : pData(new PrivateData())
 {
     if (parameterCount > 0)
     {
diff --git a/source/libs/distrho/src/DistrhoPluginInternal.hpp b/source/libs/distrho/src/DistrhoPluginInternal.hpp
index c5d69b820..690976ae1 100644
--- a/source/libs/distrho/src/DistrhoPluginInternal.hpp
+++ b/source/libs/distrho/src/DistrhoPluginInternal.hpp
@@ -28,7 +28,7 @@ START_NAMESPACE_DISTRHO
 extern uint32_t d_lastBufferSize;
 extern double   d_lastSampleRate;
 
-struct PluginPrivateData {
+struct Plugin::PrivateData {
     uint32_t bufferSize;
     double   sampleRate;
 
@@ -49,9 +49,9 @@ struct PluginPrivateData {
     uint32_t latency;
 #endif
 
-    TimePos  timePos;
+    TimePos timePos;
 
-    PluginPrivateData()
+    PrivateData()
         : bufferSize(d_lastBufferSize),
           sampleRate(d_lastSampleRate),
           parameterCount(0),
@@ -73,7 +73,7 @@ struct PluginPrivateData {
         assert(sampleRate != 0.0);
     }
 
-    ~PluginPrivateData()
+    ~PrivateData()
     {
         if (parameterCount > 0 && parameters != nullptr)
             delete[] parameters;
@@ -344,7 +344,7 @@ public:
 
 protected:
     Plugin* const kPlugin;
-    PluginPrivateData* const kData;
+    Plugin::PrivateData* const kData;
 
 private:
     static const d_string        sFallbackString;
diff --git a/source/libs/distrho/src/DistrhoPluginVST.cpp b/source/libs/distrho/src/DistrhoPluginVST.cpp
index 599f8519a..7a8e33702 100644
--- a/source/libs/distrho/src/DistrhoPluginVST.cpp
+++ b/source/libs/distrho/src/DistrhoPluginVST.cpp
@@ -223,6 +223,13 @@ protected:
 #if DISTRHO_PLUGIN_IS_SYNTH
         // TODO
 #endif
+        return;
+
+        // unused
+        (void)onOff;
+        (void)channel;
+        (void)note;
+        (void)velocity;
     }
 
     void uiResize(unsigned int width, unsigned int height)
diff --git a/source/libs/distrho/src/DistrhoUI.cpp b/source/libs/distrho/src/DistrhoUI.cpp
index 53409512f..2d4dea20e 100644
--- a/source/libs/distrho/src/DistrhoUI.cpp
+++ b/source/libs/distrho/src/DistrhoUI.cpp
@@ -27,7 +27,7 @@ double d_lastUiSampleRate = 0.0;
 // UI
 
 UI::UI()
-    : pData(new UIPrivateData)
+    : pData(new PrivateData())
 {
 #if (defined(DISTRHO_PLUGIN_TARGET_DSSI) || defined(DISTRHO_PLUGIN_TARGET_LV2))
     pData->parameterOffset = DISTRHO_PLUGIN_NUM_INPUTS + DISTRHO_PLUGIN_NUM_OUTPUTS;
diff --git a/source/libs/distrho/src/DistrhoUIInternal.hpp b/source/libs/distrho/src/DistrhoUIInternal.hpp
index aa176ba71..da6bc7af7 100644
--- a/source/libs/distrho/src/DistrhoUIInternal.hpp
+++ b/source/libs/distrho/src/DistrhoUIInternal.hpp
@@ -19,7 +19,10 @@
 
 #include "DistrhoDefines.h"
 
-#ifdef DISTRHO_UI_OPENGL
+#if defined(DISTRHO_UI_EXTERNAL)
+# include "../DistrhoUI.hpp"
+// TODO
+#elif defined(DISTRHO_UI_OPENGL)
 # include "../DistrhoUIOpenGL.hpp"
 # include "../dgl/App.hpp"
 # include "../dgl/Window.hpp"
@@ -43,7 +46,7 @@ extern double d_lastUiSampleRate;
 
 // -------------------------------------------------
 
-struct UIPrivateData {
+struct UI::PrivateData {
     // DSP
     double   sampleRate;
     uint32_t parameterOffset;
@@ -56,7 +59,7 @@ struct UIPrivateData {
     uiResizeFunc  uiResizeCallbackFunc;
     void*         ptr;
 
-    UIPrivateData()
+    PrivateData()
         : sampleRate(d_lastUiSampleRate),
           parameterOffset(0),
           editParamCallbackFunc(nullptr),
@@ -69,7 +72,7 @@ struct UIPrivateData {
         assert(sampleRate != 0.0);
     }
 
-    ~UIPrivateData()
+    ~PrivateData()
     {
     }
 
@@ -214,17 +217,26 @@ public:
 
     void idle()
     {
-#ifdef DISTRHO_UI_QT
+#if defined(DISTRHO_UI_EXTERNAL)
+        // TODO - idle OSC
+#elif defined(DISTRHO_UI_OPENGL)
+        glApp.idle();
+#else
         assert(kUi != nullptr);
 
         if (kUi != nullptr)
             kUi->d_uiIdle();
-#else
-        glApp.idle();
 #endif
     }
 
-#ifdef DISTRHO_UI_QT
+#if defined(DISTRHO_UI_EXTERNAL)
+    // needed?
+#elif defined(DISTRHO_UI_OPENGL)
+    intptr_t getWinId()
+    {
+        return glWindow.getWindowId();
+    }
+#else
     QtUI* getQtUI() const
     {
         return (QtUI*)kUi;
@@ -234,24 +246,19 @@ public:
     {
         return ((QtUI*)kUi)->d_resizable();
     }
-#else
-    intptr_t getWinId()
-    {
-        return glWindow.getWindowId();
-    }
 #endif
 
     // ---------------------------------------------
 
-private:
 #ifdef DISTRHO_UI_OPENGL
+private:
     App    glApp;
     Window glWindow;
 #endif
 
 protected:
     UI* const kUi;
-    UIPrivateData* const kData;
+    UI::PrivateData* const kData;
 };
 
 // -------------------------------------------------