diff --git a/resources/resources.qrc b/resources/resources.qrc
index 796bb706f..692a85268 100644
--- a/resources/resources.qrc
+++ b/resources/resources.qrc
@@ -87,11 +87,11 @@
         <file>bitmaps/button_file_down-white.png</file>
         <file>bitmaps/button_file_hover-black.png</file>
         <file>bitmaps/button_file_hover-white.png</file>
-        <file>scalable/button_gui-black.svg</file>
+        <!--<file>scalable/button_gui-black.svg</file>-->
         <file>scalable/button_gui-white.svg</file>
-        <file>scalable/button_gui_down-black.svg</file>
+        <!--<file>scalable/button_gui_down-black.svg</file>-->
         <file>scalable/button_gui_down-white.svg</file>
-        <file>scalable/button_gui_hover-black.svg</file>
+        <!--<file>scalable/button_gui_hover-black.svg</file>-->
         <file>scalable/button_gui_hover-white.svg</file>
 
         <file>scalable/button_off.svg</file>
diff --git a/source/frontend/Makefile b/source/frontend/Makefile
index c51484a54..73da112f9 100644
--- a/source/frontend/Makefile
+++ b/source/frontend/Makefile
@@ -156,17 +156,21 @@ endif
 
 ifeq ($(USING_JUCE),true)
 LIBS += $(MODULEDIR)/juce_audio_basics.a
+ifeq ($(USING_JUCE_AUDIO_DEVICES),true)
 LIBS += $(MODULEDIR)/juce_audio_devices.a
+endif
 LIBS += $(MODULEDIR)/juce_audio_processors.a
 LIBS += $(MODULEDIR)/juce_core.a
 LIBS += $(MODULEDIR)/juce_data_structures.a
 LIBS += $(MODULEDIR)/juce_events.a
 LIBS += $(MODULEDIR)/juce_graphics.a
 LIBS += $(MODULEDIR)/juce_gui_basics.a
-ifeq ($(MACOS),true)
+ifeq ($(USING_JUCE_GUI_EXTRA),true)
 LIBS += $(MODULEDIR)/juce_gui_extra.a
 endif
-else
+endif
+
+ifneq ($(USING_JUCE_AUDIO_DEVICES),true)
 LIBS += $(MODULEDIR)/rtaudio.a
 LIBS += $(MODULEDIR)/rtmidi.a
 endif
@@ -188,17 +192,21 @@ LINK_FLAGS += $(X11_LIBS)
 
 ifeq ($(USING_JUCE),true)
 LINK_FLAGS += $(JUCE_AUDIO_BASICS_LIBS)
+ifeq ($(USING_JUCE_AUDIO_DEVICES),true)
 LINK_FLAGS += $(JUCE_AUDIO_DEVICES_LIBS)
+endif
 LINK_FLAGS += $(JUCE_AUDIO_PROCESSORS_LIBS)
 LINK_FLAGS += $(JUCE_CORE_LIBS)
 LINK_FLAGS += $(JUCE_DATA_STRUCTURES_LIBS)
 LINK_FLAGS += $(JUCE_EVENTS_LIBS)
 LINK_FLAGS += $(JUCE_GRAPHICS_LIBS)
 LINK_FLAGS += $(JUCE_GUI_BASICS_LIBS)
-ifeq ($(MACOS),true)
+ifeq ($(USING_JUCE_GUI_EXTRA),true)
 LINK_FLAGS += $(JUCE_GUI_EXTRA_LIBS)
 endif
-else
+endif
+
+ifneq ($(USING_JUCE_AUDIO_DEVICES),true)
 LINK_FLAGS += $(RTAUDIO_LIBS)
 LINK_FLAGS += $(RTMIDI_LIBS)
 endif
diff --git a/source/frontend/carla_app.cpp b/source/frontend/carla_app.cpp
index 31f722568..15260332f 100644
--- a/source/frontend/carla_app.cpp
+++ b/source/frontend/carla_app.cpp
@@ -248,18 +248,30 @@ QApplication* CarlaApplication::createApp(const QString& appName, int& argc, cha
     QApplication::setAttribute(Qt::AA_UseHighDpiPixmaps);
 #endif
 
-    /*
-    // TODO
-    args = sys.argv[:]
+#ifdef CARLA_OS_WIN
+    static int r_argc = argc + 2;
+    static char** const r_argv = static_cast<char**>(calloc(sizeof(char*), r_argc));
+    static char argvExtra1[] = "-platform\0";
+    static char argvExtra2[] = "windows:fontengine=freetype\0";
+    for (int i=0; i<argc; ++i)
+        r_argv[i] = argv[i];
+    r_argv[argc] = argvExtra1;
+    r_argv[argc] = argvExtra2;
+#else
+# define r_argc argc
+# define r_argv argv
+#endif
 
-    if WINDOWS:
-        args += ["-platform", "windows:fontengine=freetype"]
-    */
-    fApp = gCarla.nogui ? new QCoreApplication(argc, argv) : new QApplication(argc, argv);
+    fApp = gCarla.nogui ? new QCoreApplication(r_argc, r_argv) : new QApplication(r_argc, r_argv);
     fApp->setApplicationName(appName);
     fApp->setApplicationVersion(CARLA_VERSION_STRING);
     fApp->setOrganizationName("falkTX");
 
+#ifndef CARLA_OS_WIN
+# undef r_argc
+# undef r_argv
+#endif
+
     if (gCarla.nogui)
         return nullptr;
 
diff --git a/source/frontend/carla_host.cpp b/source/frontend/carla_host.cpp
index 7ff103455..013e2433c 100644
--- a/source/frontend/carla_host.cpp
+++ b/source/frontend/carla_host.cpp
@@ -471,9 +471,9 @@ struct CarlaHostWindow::PrivateData {
 
         updateStyle();
 
-        ui.rack->setStyleSheet("  \
+        ui.rack->setStyleSheet("      \
         CarlaRackList#CarlaRackList { \
-            background-color: black;    \
+            background-color: black;  \
         }                             \
         ");
 
@@ -693,7 +693,7 @@ struct CarlaHostWindow::PrivateData {
         projectLoadingStarted();
         fIsProjectLoading = true;
 
-        if (! carla_load_project(fProjectFilename.toUtf8()))
+        if (! carla_load_project(host.handle, fProjectFilename.toUtf8()))
         {
             fIsProjectLoading = false;
             projectLoadingFinished();
@@ -702,7 +702,7 @@ struct CarlaHostWindow::PrivateData {
                              QMessageBox::Critical,
                              tr("Error"),
                              tr("Failed to load project"),
-                             carla_get_last_error(),
+                             carla_get_last_error(host.handle),
                              QMessageBox::Ok, QMessageBox::Ok);
         }
     }
@@ -770,7 +770,7 @@ struct CarlaHostWindow::PrivateData {
     {
         killTimers();
 
-        if (carla_is_engine_running())
+        if (carla_is_engine_running(host.handle))
         {
             if (fCustomStopAction == CUSTOM_ACTION_PROJECT_LOAD)
             {
@@ -782,16 +782,16 @@ struct CarlaHostWindow::PrivateData {
                 projectLoadingStarted();
             }
 
-            if (! carla_remove_all_plugins())
+            if (! carla_remove_all_plugins(host.handle))
             {
                 ui.text_logs->appendPlainText("Failed to remove all plugins, error was:");
-                ui.text_logs->appendPlainText(carla_get_last_error());
+                ui.text_logs->appendPlainText(carla_get_last_error(host.handle));
             }
 
-            if (! carla_engine_close())
+            if (! carla_engine_close(host.handle))
             {
                 ui.text_logs->appendPlainText("Failed to stop engine, error was:");
-                ui.text_logs->appendPlainText(carla_get_last_error());
+                ui.text_logs->appendPlainText(carla_get_last_error(host.handle));
             }
         }
 
@@ -803,7 +803,7 @@ struct CarlaHostWindow::PrivateData {
         {
             hostWindow->slot_engineStart();
             loadProjectNow();
-            carla_nsm_ready(NSM_CALLBACK_OPEN);
+            carla_nsm_ready(host.handle, NSM_CALLBACK_OPEN);
         }
 
         fCustomStopAction = CUSTOM_ACTION_NONE;
@@ -1014,10 +1014,10 @@ struct CarlaHostWindow::PrivateData {
     {
         if (! ui.l_transport_time->isVisible())
             return;
-        if (carla_isZero(fSampleRate) or ! carla_is_engine_running())
+        if (carla_isZero(fSampleRate) or ! carla_is_engine_running(host.handle))
             return;
 
-        const CarlaTransportInfo* const timeInfo = carla_get_transport_info();
+        const CarlaTransportInfo* const timeInfo = carla_get_transport_info(host.handle);
         const bool     playing  = timeInfo->playing;
         const uint64_t frame    = timeInfo->frame;
         const double   bpm      = timeInfo->bpm;
@@ -1193,15 +1193,15 @@ struct CarlaHostWindow::PrivateData {
     {
         if (! ui.pb_dsp_load->isVisible())
             return;
-        if (! carla_is_engine_running())
+        if (! carla_is_engine_running(host.handle))
             return;
-        const CarlaRuntimeEngineInfo* const info = carla_get_runtime_engine_info();
+        const CarlaRuntimeEngineInfo* const info = carla_get_runtime_engine_info(host.handle);
         refreshRuntimeInfo(info->load, info->xruns);
     }
 
     void idleFast()
     {
-        carla_engine_idle();
+        carla_engine_idle(host.handle);
         refreshTransport();
 
         if (fPluginCount == 0 || fCurrentlyRemovingAllPlugins)
@@ -1514,7 +1514,7 @@ CarlaHostWindow::CarlaHostWindow(CarlaHost& host, const bool withCanvas, QWidget
     // For NSM we wait for the open message
     if (NSM_URL != nullptr && host.nsmOK)
     {
-        carla_nsm_ready(NSM_CALLBACK_INIT);
+        carla_nsm_ready(host.handle, NSM_CALLBACK_INIT);
         return;
     }
 
@@ -1634,7 +1634,7 @@ void CarlaHostWindow::closeEvent(QCloseEvent* const event)
         event->ignore();
 
         for i in reversed(range(self->fPluginCount)):
-            carla_show_custom_ui(i, false);
+            carla_show_custom_ui(self->host.handle, i, false);
 
         QTimer::singleShot(100, SIGNAL(close()));
         return;
@@ -1644,7 +1644,7 @@ void CarlaHostWindow::closeEvent(QCloseEvent* const event)
     self->killTimers();
     self->saveSettings();
 
-    if (carla_is_engine_running() && ! (self->host.isControl or self->host.isPlugin))
+    if (carla_is_engine_running(self->host.handle) && ! (self->host.isControl or self->host.isPlugin))
     {
         if (! slot_engineStop(true))
         {
@@ -1691,14 +1691,14 @@ void CarlaHostWindow::slot_engineStart()
     self->fFirstEngineInit = false;
     self->ui.text_logs->appendPlainText("======= Starting engine =======");
 
-    if (carla_engine_init(audioDriver.toUtf8(), self->fClientName.toUtf8()))
+    if (carla_engine_init(self->host.handle, audioDriver.toUtf8(), self->fClientName.toUtf8()))
     {
         if (firstInit && ! (self->host.isControl or self->host.isPlugin))
         {
             QSafeSettings settings;
             const double lastBpm = settings.valueDouble("LastBPM", 120.0);
             if (lastBpm >= 20.0)
-                carla_transport_bpm(lastBpm);
+                carla_transport_bpm(self->host.handle, lastBpm);
         }
         return;
     }
@@ -1708,7 +1708,7 @@ void CarlaHostWindow::slot_engineStart()
         return;
     }
 
-    const QCarlaString audioError(carla_get_last_error());
+    const QCarlaString audioError(carla_get_last_error(self->host.handle));
 
     if (audioError.isNotEmpty())
     {
@@ -1751,7 +1751,7 @@ bool CarlaHostWindow::slot_engineStop(const bool forced)
 
 void CarlaHostWindow::slot_engineConfig()
 {
-    RuntimeDriverSettingsW dialog(self->fParentOrSelf);
+    RuntimeDriverSettingsW dialog(self->host.handle, self->fParentOrSelf);
 
     if (dialog.exec())
         return;
@@ -1761,21 +1761,21 @@ void CarlaHostWindow::slot_engineConfig()
     double sampleRate;
     dialog.getValues(audioDevice, bufferSize, sampleRate);
 
-    if (carla_is_engine_running())
+    if (carla_is_engine_running(self->host.handle))
     {
-        carla_set_engine_buffer_size_and_sample_rate(bufferSize, sampleRate);
+        carla_set_engine_buffer_size_and_sample_rate(self->host.handle, bufferSize, sampleRate);
     }
     else
     {
-        carla_set_engine_option(ENGINE_OPTION_AUDIO_DEVICE, 0, audioDevice.toUtf8());
-        carla_set_engine_option(ENGINE_OPTION_AUDIO_BUFFER_SIZE, static_cast<int>(bufferSize), "");
-        carla_set_engine_option(ENGINE_OPTION_AUDIO_SAMPLE_RATE, static_cast<int>(sampleRate), "");
+        carla_set_engine_option(self->host.handle, ENGINE_OPTION_AUDIO_DEVICE, 0, audioDevice.toUtf8());
+        carla_set_engine_option(self->host.handle, ENGINE_OPTION_AUDIO_BUFFER_SIZE, static_cast<int>(bufferSize), "");
+        carla_set_engine_option(self->host.handle, ENGINE_OPTION_AUDIO_SAMPLE_RATE, static_cast<int>(sampleRate), "");
     }
 }
 
 bool CarlaHostWindow::slot_engineStopTryAgain()
 {
-    if (carla_is_engine_running() && ! carla_set_engine_about_to_close())
+    if (carla_is_engine_running(self->host.handle) && ! carla_set_engine_about_to_close(self->host.handle))
     {
         QTimer::singleShot(0, this, SLOT(slot_engineStopTryAgain()));
         return false;
@@ -2145,8 +2145,8 @@ void CarlaHostWindow::slot_configureCarla()
 
     if (self->host.processMode == ENGINE_PROCESS_MODE_CONTINUOUS_RACK && self->host.isPlugin)
         pass();
-    else if (carla_is_engine_running())
-        carla_patchbay_refresh(self->fExternalPatchbay);
+    else if (carla_is_engine_running(self->host.handle))
+        carla_patchbay_refresh(self->host.handle, self->fExternalPatchbay);
 }
 
 //---------------------------------------------------------------------------------------------------------------------
@@ -2191,72 +2191,72 @@ void CarlaHostWindow::slot_fileTreeDoubleClicked(QModelIndex* modelIndex)
 
 void CarlaHostWindow::slot_transportPlayPause(const bool toggled)
 {
-    if (self->host.isPlugin || ! carla_is_engine_running())
+    if (self->host.isPlugin || ! carla_is_engine_running(self->host.handle))
         return;
 
     if (toggled)
-        carla_transport_play();
+        carla_transport_play(self->host.handle);
     else
-        carla_transport_pause();
+        carla_transport_pause(self->host.handle);
 
     self->refreshTransport();
 }
 
 void CarlaHostWindow::slot_transportStop()
 {
-    if (self->host.isPlugin || ! carla_is_engine_running())
+    if (self->host.isPlugin || ! carla_is_engine_running(self->host.handle))
         return;
 
-    carla_transport_pause();
-    carla_transport_relocate(0);
+    carla_transport_pause(self->host.handle);
+    carla_transport_relocate(self->host.handle, 0);
 
     self->refreshTransport();
 }
 
 void CarlaHostWindow::slot_transportBackwards()
 {
-    if (self->host.isPlugin || ! carla_is_engine_running())
+    if (self->host.isPlugin || ! carla_is_engine_running(self->host.handle))
         return;
 
-    uint64_t newFrame = carla_get_current_transport_frame();
+    uint64_t newFrame = carla_get_current_transport_frame(self->host.handle);
 
     if (newFrame > 100000)
         newFrame -= 100000;
     else
         newFrame = 0;
 
-    carla_transport_relocate(newFrame);
+    carla_transport_relocate(self->host.handle, newFrame);
 }
 
 void CarlaHostWindow::slot_transportBpmChanged(const qreal newValue)
 {
-    carla_transport_bpm(newValue);
+    carla_transport_bpm(self->host.handle, newValue);
 }
 
 void CarlaHostWindow::slot_transportForwards()
 {
-    if (carla_isZero(self->fSampleRate) || self->host.isPlugin || ! carla_is_engine_running())
+    if (carla_isZero(self->fSampleRate) || self->host.isPlugin || ! carla_is_engine_running(self->host.handle))
         return;
 
-    const uint64_t newFrame = carla_get_current_transport_frame() + uint64_t(self->fSampleRate*2.5);
-    carla_transport_relocate(newFrame);
+    const uint64_t newFrame = carla_get_current_transport_frame(self->host.handle) + uint64_t(self->fSampleRate*2.5);
+    carla_transport_relocate(self->host.handle, newFrame);
 }
 
 void CarlaHostWindow::slot_transportJackEnabled(const bool clicked)
 {
-    if (! carla_is_engine_running())
+    if (! carla_is_engine_running(self->host.handle))
         return;
     self->host.transportMode = clicked ? ENGINE_TRANSPORT_MODE_JACK : ENGINE_TRANSPORT_MODE_INTERNAL;
-    carla_set_engine_option(ENGINE_OPTION_TRANSPORT_MODE, self->host.transportMode, self->host.transportExtra.toUtf8());
+    carla_set_engine_option(self->host.handle, ENGINE_OPTION_TRANSPORT_MODE, self->host.transportMode, self->host.transportExtra.toUtf8());
 }
 
 void CarlaHostWindow::slot_transportLinkEnabled(const bool clicked)
 {
-    if (! carla_is_engine_running())
+    if (! carla_is_engine_running(self->host.handle))
         return;
     const char* const extra = clicked ? ":link:" : "";
     self->host.transportExtra = extra;
-    carla_set_engine_option(ENGINE_OPTION_TRANSPORT_MODE, self->host.transportMode, self->host.transportExtra.toUtf8());
+    carla_set_engine_option(self->host.handle, ENGINE_OPTION_TRANSPORT_MODE, self->host.transportMode, self->host.transportExtra.toUtf8());
 }
 
 //---------------------------------------------------------------------------------------------------------------------
@@ -2264,7 +2264,7 @@ void CarlaHostWindow::slot_transportLinkEnabled(const bool clicked)
 
 void CarlaHostWindow::slot_xrunClear()
 {
-    carla_clear_engine_xruns();
+    carla_clear_engine_xruns(self->host.handle);
 }
 
 //---------------------------------------------------------------------------------------------------------------------
@@ -2513,22 +2513,30 @@ CarlaHost& initHost(const QString initName, const bool isControl, const bool isP
     host.isControl = isControl;
     host.isPlugin  = isPlugin;
 
-    carla_set_engine_callback(_engineCallback, &host);
-    carla_set_file_callback(_fileCallback, nullptr);
+    // TODO
+    if (isPlugin)
+        pass();
+    else if (isControl)
+        pass();
+    else
+        host.handle = carla_standalone_host_init();
+
+    carla_set_engine_callback(host.handle, _engineCallback, &host);
+    carla_set_file_callback(host.handle, _fileCallback, nullptr);
 
     // If it's a plugin the paths are already set
     if (! isPlugin)
     {
         host.pathBinaries  = pathBinaries;
         host.pathResources = pathResources;
-        carla_set_engine_option(ENGINE_OPTION_PATH_BINARIES, 0, pathBinaries.toUtf8());
-        carla_set_engine_option(ENGINE_OPTION_PATH_RESOURCES, 0, pathResources.toUtf8());
+        carla_set_engine_option(host.handle, ENGINE_OPTION_PATH_BINARIES, 0, pathBinaries.toUtf8());
+        carla_set_engine_option(host.handle, ENGINE_OPTION_PATH_RESOURCES, 0, pathResources.toUtf8());
 
         if (! isControl)
         {
             const pid_t pid = getpid();
             if (pid > 0)
-                host.nsmOK = carla_nsm_init(static_cast<uint64_t>(pid), initName.toUtf8());
+                host.nsmOK = carla_nsm_init(host.handle, static_cast<uint64_t>(pid), initName.toUtf8());
         }
     }
 
@@ -2609,20 +2617,20 @@ void loadHostSettings(CarlaHost& host)
 
 void setHostSettings(const CarlaHost& host)
 {
-    carla_set_engine_option(ENGINE_OPTION_FORCE_STEREO,          host.forceStereo,         "");
-    carla_set_engine_option(ENGINE_OPTION_MAX_PARAMETERS,        static_cast<int>(host.maxParameters), "");
-    carla_set_engine_option(ENGINE_OPTION_PREFER_PLUGIN_BRIDGES, host.preferPluginBridges, "");
-    carla_set_engine_option(ENGINE_OPTION_PREFER_UI_BRIDGES,     host.preferUIBridges,     "");
-    carla_set_engine_option(ENGINE_OPTION_PREVENT_BAD_BEHAVIOUR, host.preventBadBehaviour, "");
-    carla_set_engine_option(ENGINE_OPTION_UI_BRIDGES_TIMEOUT,    host.uiBridgesTimeout,    "");
-    carla_set_engine_option(ENGINE_OPTION_UIS_ALWAYS_ON_TOP,     host.uisAlwaysOnTop,      "");
+    carla_set_engine_option(host.handle, ENGINE_OPTION_FORCE_STEREO,          host.forceStereo,         "");
+    carla_set_engine_option(host.handle, ENGINE_OPTION_MAX_PARAMETERS,        static_cast<int>(host.maxParameters), "");
+    carla_set_engine_option(host.handle, ENGINE_OPTION_PREFER_PLUGIN_BRIDGES, host.preferPluginBridges, "");
+    carla_set_engine_option(host.handle, ENGINE_OPTION_PREFER_UI_BRIDGES,     host.preferUIBridges,     "");
+    carla_set_engine_option(host.handle, ENGINE_OPTION_PREVENT_BAD_BEHAVIOUR, host.preventBadBehaviour, "");
+    carla_set_engine_option(host.handle, ENGINE_OPTION_UI_BRIDGES_TIMEOUT,    host.uiBridgesTimeout,    "");
+    carla_set_engine_option(host.handle, ENGINE_OPTION_UIS_ALWAYS_ON_TOP,     host.uisAlwaysOnTop,      "");
 
-    if (host.isPlugin || host.isRemote || carla_is_engine_running())
+    if (host.isPlugin || host.isRemote || carla_is_engine_running(host.handle))
         return;
 
-    carla_set_engine_option(ENGINE_OPTION_PROCESS_MODE,          host.nextProcessMode,     "");
-    carla_set_engine_option(ENGINE_OPTION_TRANSPORT_MODE,        host.transportMode,       host.transportExtra.toUtf8());
-    carla_set_engine_option(ENGINE_OPTION_DEBUG_CONSOLE_OUTPUT,  host.showLogs,            "");
+    carla_set_engine_option(host.handle, ENGINE_OPTION_PROCESS_MODE,          host.nextProcessMode,     "");
+    carla_set_engine_option(host.handle, ENGINE_OPTION_TRANSPORT_MODE,        host.transportMode,       host.transportExtra.toUtf8());
+    carla_set_engine_option(host.handle, ENGINE_OPTION_DEBUG_CONSOLE_OUTPUT,  host.showLogs,            "");
 }
 
 //---------------------------------------------------------------------------------------------------------------------
@@ -2707,9 +2715,9 @@ QString setEngineSettings(CarlaHost& host)
     else
         portNumUDP = settings.valueIntPositive(CARLA_KEY_OSC_UDP_PORT_NUMBER, CARLA_DEFAULT_OSC_UDP_PORT_NUMBER);
 
-    carla_set_engine_option(ENGINE_OPTION_OSC_ENABLED, oscEnabled ? 1 : 0, "");
-    carla_set_engine_option(ENGINE_OPTION_OSC_PORT_TCP, portNumTCP, "");
-    carla_set_engine_option(ENGINE_OPTION_OSC_PORT_UDP, portNumUDP, "");
+    carla_set_engine_option(host.handle, ENGINE_OPTION_OSC_ENABLED, oscEnabled ? 1 : 0, "");
+    carla_set_engine_option(host.handle, ENGINE_OPTION_OSC_PORT_TCP, portNumTCP, "");
+    carla_set_engine_option(host.handle, ENGINE_OPTION_OSC_PORT_UDP, portNumUDP, "");
 
     //-----------------------------------------------------------------------------------------------------------------
     // wine settings
@@ -2721,15 +2729,15 @@ QString setEngineSettings(CarlaHost& host)
     const int optWineBaseRtPrio = settings.valueIntPositive(CARLA_KEY_WINE_BASE_RT_PRIO,   CARLA_DEFAULT_WINE_BASE_RT_PRIO);
     const int optWineServerRtPrio = settings.valueIntPositive(CARLA_KEY_WINE_SERVER_RT_PRIO, CARLA_DEFAULT_WINE_SERVER_RT_PRIO);
 
-    carla_set_engine_option(ENGINE_OPTION_WINE_EXECUTABLE, 0, optWineExecutable.toUtf8());
-    carla_set_engine_option(ENGINE_OPTION_WINE_AUTO_PREFIX, optWineAutoPrefix ? 1 : 0, "");
+    carla_set_engine_option(host.handle, ENGINE_OPTION_WINE_EXECUTABLE, 0, optWineExecutable.toUtf8());
+    carla_set_engine_option(host.handle, ENGINE_OPTION_WINE_AUTO_PREFIX, optWineAutoPrefix ? 1 : 0, "");
     /*
     // TODO
-    carla_set_engine_option(ENGINE_OPTION_WINE_FALLBACK_PREFIX, 0, os.path.expanduser(optWineFallbackPrefix));
+    carla_set_engine_option(host.handle, ENGINE_OPTION_WINE_FALLBACK_PREFIX, 0, os.path.expanduser(optWineFallbackPrefix));
     */
-    carla_set_engine_option(ENGINE_OPTION_WINE_RT_PRIO_ENABLED, optWineRtPrioEnabled ? 1 : 0, "");
-    carla_set_engine_option(ENGINE_OPTION_WINE_BASE_RT_PRIO, optWineBaseRtPrio, "");
-    carla_set_engine_option(ENGINE_OPTION_WINE_SERVER_RT_PRIO, optWineServerRtPrio, "");
+    carla_set_engine_option(host.handle, ENGINE_OPTION_WINE_RT_PRIO_ENABLED, optWineRtPrioEnabled ? 1 : 0, "");
+    carla_set_engine_option(host.handle, ENGINE_OPTION_WINE_BASE_RT_PRIO, optWineBaseRtPrio, "");
+    carla_set_engine_option(host.handle, ENGINE_OPTION_WINE_SERVER_RT_PRIO, optWineServerRtPrio, "");
 
     //-----------------------------------------------------------------------------------------------------------------
     // driver and device settings
@@ -2750,16 +2758,16 @@ QString setEngineSettings(CarlaHost& host)
     const bool audioTripleBuffer = settings.valueBool(QString("%1/TripleBuffer").arg(prefix), CARLA_DEFAULT_AUDIO_TRIPLE_BUFFER);
 
     // Only setup audio things if engine is not running
-    if (! carla_is_engine_running())
+    if (! carla_is_engine_running(host.handle))
     {
-        carla_set_engine_option(ENGINE_OPTION_AUDIO_DRIVER, 0, audioDriver.toUtf8());
-        carla_set_engine_option(ENGINE_OPTION_AUDIO_DEVICE, 0, audioDevice.toUtf8());
+        carla_set_engine_option(host.handle, ENGINE_OPTION_AUDIO_DRIVER, 0, audioDriver.toUtf8());
+        carla_set_engine_option(host.handle, ENGINE_OPTION_AUDIO_DEVICE, 0, audioDevice.toUtf8());
 
         if (! audioDriver.startsWith("JACK"))
         {
-            carla_set_engine_option(ENGINE_OPTION_AUDIO_BUFFER_SIZE, audioBufferSize, "");
-            carla_set_engine_option(ENGINE_OPTION_AUDIO_SAMPLE_RATE, audioSampleRate, "");
-            carla_set_engine_option(ENGINE_OPTION_AUDIO_TRIPLE_BUFFER, audioTripleBuffer ? 1 : 0, "");
+            carla_set_engine_option(host.handle, ENGINE_OPTION_AUDIO_BUFFER_SIZE, audioBufferSize, "");
+            carla_set_engine_option(host.handle, ENGINE_OPTION_AUDIO_SAMPLE_RATE, audioSampleRate, "");
+            carla_set_engine_option(host.handle, ENGINE_OPTION_AUDIO_TRIPLE_BUFFER, audioTripleBuffer ? 1 : 0, "");
         }
     }
 
@@ -2769,7 +2777,10 @@ QString setEngineSettings(CarlaHost& host)
     if (audioDriver != "JACK" && host.transportMode == ENGINE_TRANSPORT_MODE_JACK)
     {
         host.transportMode = ENGINE_TRANSPORT_MODE_INTERNAL;
-        carla_set_engine_option(ENGINE_OPTION_TRANSPORT_MODE, ENGINE_TRANSPORT_MODE_INTERNAL, host.transportExtra.toUtf8());
+        carla_set_engine_option(host.handle,
+                                ENGINE_OPTION_TRANSPORT_MODE,
+                                ENGINE_TRANSPORT_MODE_INTERNAL,
+                                host.transportExtra.toUtf8());
     }
 
     //-----------------------------------------------------------------------------------------------------------------
@@ -2802,16 +2813,16 @@ void runHostWithoutUI(CarlaHost& host)
 
     const QString audioDriver = setEngineSettings(host);
 
-    if (! carla_engine_init(audioDriver.toUtf8(), "Carla"))
+    if (! carla_engine_init(host.handle, audioDriver.toUtf8(), "Carla"))
     {
-        carla_stdout("Engine failed to initialize, possible reasons:\n%s", carla_get_last_error());
+        carla_stdout("Engine failed to initialize, possible reasons:\n%s", carla_get_last_error(host.handle));
         std::exit(1);
     }
 
-    if (! carla_load_project(projectFile.toUtf8()))
+    if (! carla_load_project(host.handle, projectFile.toUtf8()))
     {
-        carla_stdout("Failed to load selected project file, possible reasons:\n%s", carla_get_last_error());
-        carla_engine_close();
+        carla_stdout("Failed to load selected project file, possible reasons:\n%s", carla_get_last_error(host.handle));
+        carla_engine_close(host.handle);
         std::exit(1);
     }
 
@@ -2820,16 +2831,16 @@ void runHostWithoutUI(CarlaHost& host)
 
     carla_stdout("Carla ready!");
 
-    while (carla_is_engine_running() && ! gCarla.term)
+    while (carla_is_engine_running(host.handle) && ! gCarla.term)
     {
-        carla_engine_idle();
+        carla_engine_idle(host.handle);
         carla_msleep(33); // 30 Hz
     }
 
     //-----------------------------------------------------------------------------------------------------------------
     // Stop
 
-    carla_engine_close();
+    carla_engine_close(host.handle);
     std::exit(0);
 }
 
diff --git a/source/frontend/carla_host.hpp b/source/frontend/carla_host.hpp
index e61794a7e..e197a841a 100644
--- a/source/frontend/carla_host.hpp
+++ b/source/frontend/carla_host.hpp
@@ -40,7 +40,7 @@
 #include "carla_shared.hpp"
 #include "carla_widgets.hpp"
 
-#include "CarlaBackend.h"
+#include "CarlaHost.h"
 #include "CarlaJuceUtils.hpp"
 
 CARLA_BACKEND_USE_NAMESPACE;
@@ -52,6 +52,9 @@ class CarlaHost : public QObject
     Q_OBJECT
 
 public:
+    // host handle
+    CarlaHostHandle handle;
+
     // info about this host object
     bool isControl;
     bool isPlugin;
diff --git a/source/frontend/carla_settings.cpp b/source/frontend/carla_settings.cpp
index da79c6320..7c7f77e44 100644
--- a/source/frontend/carla_settings.cpp
+++ b/source/frontend/carla_settings.cpp
@@ -258,9 +258,11 @@ void DriverSettingsW::slot_updateDeviceInfo()
 
 struct RuntimeDriverSettingsW::PrivateData {
     Ui::DriverSettingsW ui;
+    const CarlaHostHandle hostHandle;
 
-    PrivateData(RuntimeDriverSettingsW* const self)
-        : ui()
+    PrivateData(RuntimeDriverSettingsW* const self, const CarlaHostHandle h)
+        : ui(),
+          hostHandle(h)
     {
         ui.setupUi(self);
     }
@@ -268,11 +270,12 @@ struct RuntimeDriverSettingsW::PrivateData {
     CARLA_DECLARE_NON_COPYABLE_WITH_LEAK_DETECTOR(PrivateData)
 };
 
-RuntimeDriverSettingsW::RuntimeDriverSettingsW(QWidget* const parent)
+RuntimeDriverSettingsW::RuntimeDriverSettingsW(const CarlaHostHandle hostHandle, QWidget* const parent)
     : QDialog(parent),
-      self(new PrivateData(this))
+      self(new PrivateData(this, hostHandle))
 {
-    const CarlaRuntimeEngineDriverDeviceInfo* const driverDeviceInfo = carla_get_runtime_engine_driver_device_info();
+    const CarlaRuntimeEngineDriverDeviceInfo* const driverDeviceInfo =
+        carla_get_runtime_engine_driver_device_info(hostHandle);
 
     QList<uint> bufferSizes;
     fillQUIntListFromUIntArray(bufferSizes, driverDeviceInfo->bufferSizes);
@@ -307,7 +310,7 @@ RuntimeDriverSettingsW::RuntimeDriverSettingsW(QWidget* const parent)
     // ----------------------------------------------------------------------------------------------------------------
     // Load runtime settings
 
-    if (carla_is_engine_running())
+    if (carla_is_engine_running(hostHandle))
     {
         self->ui.cb_device->addItem(driverDeviceInfo->name);
         self->ui.cb_device->setCurrentIndex(0);
@@ -393,7 +396,7 @@ void RuntimeDriverSettingsW::getValues(QString& retAudioDevice, uint& retBufferS
 
 void RuntimeDriverSettingsW::slot_showDevicePanel()
 {
-    carla_show_engine_device_control_panel();
+    carla_show_engine_device_control_panel(self->hostHandle);
 }
 
 // --------------------------------------------------------------------------------------------------------------------
diff --git a/source/frontend/carla_settings.hpp b/source/frontend/carla_settings.hpp
index 2e7a2bae4..106275466 100644
--- a/source/frontend/carla_settings.hpp
+++ b/source/frontend/carla_settings.hpp
@@ -37,6 +37,7 @@
 //---------------------------------------------------------------------------------------------------------------------
 // Imports (Custom)
 
+#include "CarlaHost.h"
 #include "CarlaJuceUtils.hpp"
 
 class CarlaHost;
@@ -71,7 +72,7 @@ class RuntimeDriverSettingsW : public QDialog
     Q_OBJECT
 
 public:
-    RuntimeDriverSettingsW(QWidget* parent = nullptr);
+    RuntimeDriverSettingsW(CarlaHostHandle hostHandle, QWidget* parent = nullptr);
     ~RuntimeDriverSettingsW() override;
 
     void getValues(QString& audioDevice, uint& bufferSize, double& sampleRate);
diff --git a/source/frontend/carla_settings_app.cpp b/source/frontend/carla_settings_app.cpp
index 5881b3ffe..b24ae99c1 100644
--- a/source/frontend/carla_settings_app.cpp
+++ b/source/frontend/carla_settings_app.cpp
@@ -15,7 +15,7 @@
  * For a full copy of the GNU General Public License see the doc/GPL.txt file.
  */
 
-#include "carla_database.hpp"
+#include "carla_settings.hpp"
 
 //---------------------------------------------------------------------------------------------------------------------
 
@@ -46,7 +46,7 @@ int main(int argc, char* argv[])
     // ----------------------------------------------------------------------------------------------------------------
     // Create GUI
 
-    PluginRefreshW gui(nullptr, host);
+    CarlaSettingsW gui(nullptr, host, true, true);
 
     // ----------------------------------------------------------------------------------------------------------------
     // Show GUI
diff --git a/source/frontend/carla_widgets.cpp b/source/frontend/carla_widgets.cpp
index 4e3a18cb1..c6e176ad1 100644
--- a/source/frontend/carla_widgets.cpp
+++ b/source/frontend/carla_widgets.cpp
@@ -90,10 +90,10 @@ struct CarlaAboutW::PrivateData {
 
         ui.l_extended->setText(carla_get_complete_license_text());
 
-        if (carla_is_engine_running() && ! host.isControl)
+        if (carla_is_engine_running(host.handle) && ! host.isControl)
         {
-            ui.le_osc_url_tcp->setText(carla_get_host_osc_url_tcp());
-            ui.le_osc_url_udp->setText(carla_get_host_osc_url_udp());
+            ui.le_osc_url_tcp->setText(carla_get_host_osc_url_tcp(host.handle));
+            ui.le_osc_url_udp->setText(carla_get_host_osc_url_udp(host.handle));
         }
         else
         {