diff --git a/c++/carla-bridge/Makefile b/c++/carla-bridge/Makefile
index 75be705..b8cae42 100644
--- a/c++/carla-bridge/Makefile
+++ b/c++/carla-bridge/Makefile
@@ -215,8 +215,8 @@ carla_bridge_toolkit-qt4__vst-x11.o: carla_bridge_toolkit-qt4.cpp
 
 OBJS_POSIX32 = \
 	carla_bridge_plugin__posix32.o carla_bridge_osc__posix32.o \
-	carla_engine__posix32.o carla_engine_thread__posix32.o carla_engine_jack__posix32.o \
-	carla_plugin__posix32.o ladspa__posix32.o dssi__posix32.o lv2__posix32.o vst__posix32.o \
+	carla_engine__posix32.o carla_engine_osc__posix32.o carla_engine_thread__posix32.o carla_engine_jack__posix32.o \
+	carla_plugin__posix32.o carla_plugin_thread__posix32.o ladspa__posix32.o dssi__posix32.o lv2__posix32.o vst__posix32.o \
 	../carla-lilv/carla_lilv_posix32.a ../carla-rtmempool/carla_rtmempool_posix32.a
 
 carla-bridge-posix32: $(OBJS_POSIX32)
@@ -231,6 +231,9 @@ carla_bridge_osc__posix32.o: carla_bridge_osc.cpp
 carla_engine__posix32.o: ../carla-engine/carla_engine.cpp
 	$(CXX) $< $(POSIX_BUILD_FLAGS) $(POSIX_32BIT_FLAGS) -c -o $@
 
+carla_engine_osc__posix32.o: ../carla-engine/carla_engine_osc.cpp
+	$(CXX) $< $(POSIX_BUILD_FLAGS) $(POSIX_32BIT_FLAGS) -c -o $@
+
 carla_engine_thread__posix32.o: ../carla-engine/carla_engine_thread.cpp
 	$(CXX) $< $(POSIX_BUILD_FLAGS) $(POSIX_32BIT_FLAGS) -c -o $@
 
@@ -240,6 +243,9 @@ carla_engine_jack__posix32.o: ../carla-engine/jack.cpp
 carla_plugin__posix32.o: ../carla-plugin/carla_plugin.cpp
 	$(CXX) $< $(POSIX_BUILD_FLAGS) $(POSIX_32BIT_FLAGS) -c -o $@
 
+carla_plugin_thread__posix32.o: ../carla-plugin/carla_plugin_thread.cpp
+	$(CXX) $< $(POSIX_BUILD_FLAGS) $(POSIX_32BIT_FLAGS) -c -o $@
+
 ladspa__posix32.o: ../carla-plugin/ladspa.cpp
 	$(CXX) $< $(POSIX_BUILD_FLAGS) $(POSIX_32BIT_FLAGS) -c -o $@
 
@@ -257,8 +263,8 @@ vst__posix32.o: ../carla-plugin/vst.cpp
 
 OBJS_POSIX64 = \
 	carla_bridge_plugin__posix64.o carla_bridge_osc__posix64.o \
-	carla_engine__posix64.o carla_engine_thread__posix64.o carla_engine_jack__posix64.o \
-	carla_plugin__posix64.o ladspa__posix64.o dssi__posix64.o lv2__posix64.o vst__posix64.o \
+	carla_engine__posix64.o carla_engine_osc__posix64.o carla_engine_thread__posix64.o carla_engine_jack__posix64.o \
+	carla_plugin__posix64.o carla_plugin_thread__posix64.o ladspa__posix64.o dssi__posix64.o lv2__posix64.o vst__posix64.o \
 	../carla-lilv/carla_lilv_posix64.a ../carla-rtmempool/carla_rtmempool_posix64.a
 
 carla-bridge-posix64: $(OBJS_POSIX64)
@@ -273,6 +279,9 @@ carla_bridge_osc__posix64.o: carla_bridge_osc.cpp
 carla_engine__posix64.o: ../carla-engine/carla_engine.cpp
 	$(CXX) $< $(POSIX_BUILD_FLAGS) $(POSIX_64BIT_FLAGS) -c -o $@
 
+carla_engine_osc__posix64.o: ../carla-engine/carla_engine_osc.cpp
+	$(CXX) $< $(POSIX_BUILD_FLAGS) $(POSIX_64BIT_FLAGS) -c -o $@
+
 carla_engine_thread__posix64.o: ../carla-engine/carla_engine_thread.cpp
 	$(CXX) $< $(POSIX_BUILD_FLAGS) $(POSIX_64BIT_FLAGS) -c -o $@
 
@@ -282,6 +291,9 @@ carla_engine_jack__posix64.o: ../carla-engine/jack.cpp
 carla_plugin__posix64.o: ../carla-plugin/carla_plugin.cpp
 	$(CXX) $< $(POSIX_BUILD_FLAGS) $(POSIX_64BIT_FLAGS) -c -o $@
 
+carla_plugin_thread__posix64.o: ../carla-plugin/carla_plugin_thread.cpp
+	$(CXX) $< $(POSIX_BUILD_FLAGS) $(POSIX_64BIT_FLAGS) -c -o $@
+
 ladspa__posix64.o: ../carla-plugin/ladspa.cpp
 	$(CXX) $< $(POSIX_BUILD_FLAGS) $(POSIX_64BIT_FLAGS) -c -o $@
 
@@ -299,8 +311,8 @@ vst__posix64.o: ../carla-plugin/vst.cpp
 
 OBJS_WIN32 = \
 	carla_bridge_plugin__win32.o carla_bridge_osc__win32.o \
-	carla_engine__win32.o carla_engine_thread__win32.o carla_engine_jack__win32.o \
-	carla_plugin__win32.o ladspa__win32.o dssi__win32.o lv2__win32.o vst__win32.o \
+	carla_engine__win32.o carla_engine_osc__win32.o carla_engine_thread__win32.o carla_engine_jack__win32.o \
+	carla_plugin__win32.o carla_plugin_thread__win32.o ladspa__win32.o dssi__win32.o lv2__win32.o vst__win32.o \
 	../carla-lilv/carla_lilv_win32.a ../carla-rtmempool/carla_rtmempool_win32.a
 
 carla-bridge-win32.exe: $(OBJS_WIN32) ../carla-jackbridge/libcarla-jackbridge-win32.dll
@@ -315,6 +327,9 @@ carla_bridge_osc__win32.o: carla_bridge_osc.cpp
 carla_engine__win32.o: ../carla-engine/carla_engine.cpp
 	$(CXX) $< $(WIN_BUILD_FLAGS) $(WIN_32BIT_FLAGS) -c -o $@
 
+carla_engine_osc__win32.o: ../carla-engine/carla_engine_osc.cpp
+	$(CXX) $< $(WIN_BUILD_FLAGS) $(WIN_32BIT_FLAGS) -c -o $@
+
 carla_engine_thread__win32.o: ../carla-engine/carla_engine_thread.cpp
 	$(CXX) $< $(WIN_BUILD_FLAGS) $(WIN_32BIT_FLAGS) -c -o $@
 
@@ -324,6 +339,9 @@ carla_engine_jack__win32.o: ../carla-engine/jack.cpp
 carla_plugin__win32.o: ../carla-plugin/carla_plugin.cpp
 	$(CXX) $< $(WIN_BUILD_FLAGS) $(WIN_32BIT_FLAGS) -c -o $@
 
+carla_plugin_thread__win32.o: ../carla-plugin/carla_plugin_thread.cpp
+	$(CXX) $< $(WIN_BUILD_FLAGS) $(WIN_32BIT_FLAGS) -c -o $@
+
 ladspa__win32.o: ../carla-plugin/ladspa.cpp
 	$(CXX) $< $(WIN_BUILD_FLAGS) $(WIN_32BIT_FLAGS) -c -o $@
 
@@ -341,8 +359,8 @@ vst__win32.o: ../carla-plugin/vst.cpp
 
 OBJS_WIN64 = \
 	carla_bridge_plugin__win64.o carla_bridge_osc__win64.o \
-	carla_engine__win64.o carla_engine_thread__win64.o carla_engine_jack__win64.o \
-	carla_plugin__win64.o ladspa__win64.o dssi__win64.o lv2__win64.o vst__win64.o \
+	carla_engine__win64.o carla_engine_osc__win64.o carla_engine_thread__win64.o carla_engine_jack__win64.o \
+	carla_plugin__win64.o carla_plugin_thread__win64.o ladspa__win64.o dssi__win64.o lv2__win64.o vst__win64.o \
 	../carla-lilv/carla_lilv_win64.a ../carla-rtmempool/carla_rtmempool_win64.a
 
 carla-bridge-win64.exe: $(OBJS_WIN64) ../carla-jackbridge/libcarla-jackbridge-win64.dll
@@ -357,6 +375,9 @@ carla_bridge_osc__win64.o: carla_bridge_osc.cpp
 carla_engine__win64.o: ../carla-engine/carla_engine.cpp
 	$(CXX) $< $(WIN_BUILD_FLAGS) $(WIN_64BIT_FLAGS) -c -o $@
 
+carla_engine_osc__win64.o: ../carla-engine/carla_engine_osc.cpp
+	$(CXX) $< $(WIN_BUILD_FLAGS) $(WIN_64BIT_FLAGS) -c -o $@
+
 carla_engine_thread__win64.o: ../carla-engine/carla_engine_thread.cpp
 	$(CXX) $< $(WIN_BUILD_FLAGS) $(WIN_64BIT_FLAGS) -c -o $@
 
@@ -366,6 +387,9 @@ carla_engine_jack__win64.o: ../carla-engine/jack.cpp
 carla_plugin__win64.o: ../carla-plugin/carla_plugin.cpp
 	$(CXX) $< $(WIN_BUILD_FLAGS) $(WIN_64BIT_FLAGS) -c -o $@
 
+carla_plugin_thread__win64.o: ../carla-plugin/carla_plugin_thread.cpp
+	$(CXX) $< $(WIN_BUILD_FLAGS) $(WIN_64BIT_FLAGS) -c -o $@
+
 ladspa__win64.o: ../carla-plugin/ladspa.cpp
 	$(CXX) $< $(WIN_BUILD_FLAGS) $(WIN_64BIT_FLAGS) -c -o $@
 
diff --git a/c++/carla-bridge/carla_bridge_plugin.cpp b/c++/carla-bridge/carla_bridge_plugin.cpp
index 776794e..20d09fd 100644
--- a/c++/carla-bridge/carla_bridge_plugin.cpp
+++ b/c++/carla-bridge/carla_bridge_plugin.cpp
@@ -37,12 +37,17 @@
 static int    qargc     = 0;
 static char** qargv     = nullptr;
 static bool   qCloseNow = false;
+static bool   qSaveNow  = false;
 
-#if defined(Q_OS_UNIX)
+#if defined(Q_OS_HAIKU) || defined(Q_OS_UNIX)
 void closeSignalHandler(int)
 {
     qCloseNow = true;
 }
+void saveSignalHandler(int)
+{
+    qSaveNow = true;
+}
 #elif defined(Q_OS_WIN)
 BOOL WINAPI closeSignalHandler(DWORD dwCtrlType)
 {
@@ -58,9 +63,10 @@ BOOL WINAPI closeSignalHandler(DWORD dwCtrlType)
 
 void initSignalHandler()
 {
-#if defined(Q_OS_UNIX)
+#if defined(Q_OS_HAIKU) || defined(Q_OS_UNIX)
     struct sigaction sint;
     struct sigaction sterm;
+    struct sigaction susr1;
 
     sint.sa_handler  = closeSignalHandler;
     sint.sa_flags    = SA_RESTART;
@@ -73,6 +79,12 @@ void initSignalHandler()
     sterm.sa_restorer = nullptr;
     sigemptyset(&sterm.sa_mask);
     sigaction(SIGTERM, &sterm, nullptr);
+
+    susr1.sa_handler  = saveSignalHandler;
+    susr1.sa_flags    = SA_RESTART;
+    susr1.sa_restorer = nullptr;
+    sigemptyset(&susr1.sa_mask);
+    sigaction(SIGUSR1, &susr1, nullptr);
 #elif defined(Q_OS_WIN)
     SetConsoleCtrlHandler(closeSignalHandler, TRUE);
 #endif
@@ -234,8 +246,9 @@ public:
         pluginGui = nullptr;
 
         m_client = this;
-        m_hasUI  = false;
         m_doQuit = false;
+        m_hasUI  = false;
+        m_qt4UI  = false;
 
         m_needsResize = false;
         m_nextSize[0] = 0;
@@ -334,7 +347,7 @@ public:
         if (plugin)
             plugin->showGui(true);
 
-        if (pluginGui)
+        if (pluginGui && m_qt4UI)
             pluginGui->show();
     }
 
@@ -343,7 +356,7 @@ public:
         qDebug("BridgePluginClient::hide()");
         CARLA_ASSERT(pluginGui);
 
-        if (pluginGui)
+        if (pluginGui && m_qt4UI)
             pluginGui->hide();
 
         if (plugin)
@@ -371,6 +384,7 @@ public:
             return;
 
         m_hasUI = true;
+        m_qt4UI = true;
 
         pluginGui->setResizable(resizable);
         pluginGui->setTitle(plugin->name());
@@ -664,6 +678,12 @@ protected:
         if (qCloseNow)
             return quit();
 
+        if (qSaveNow)
+        {
+            // TODO
+            qSaveNow = false;
+        }
+
         if (event->timerId() == msgTimerGUI)
         {
 #if 0
@@ -711,6 +731,7 @@ private:
 
     bool m_doQuit;
     bool m_hasUI;
+    bool m_qt4UI;
     bool m_needsResize;
     int  m_nextSize[2];
 
@@ -802,7 +823,7 @@ int main(int argc, char* argv[])
     void* extraStuff = nullptr;
 
 #if 1 // TESTING
-    static const char* const dssiGUI = "/usr/lib/dssi/amsynth_dssi/amsynth_dssi_gtk";
+    static const char* const dssiGUI = "/usr/lib/dssi/calf/calf_gtk";
     extraStuff = (void*)dssiGUI;
 #endif
 
diff --git a/c++/carla-engine/carla_engine.cpp b/c++/carla-engine/carla_engine.cpp
index 4bf29a3..65d58c8 100644
--- a/c++/carla-engine/carla_engine.cpp
+++ b/c++/carla-engine/carla_engine.cpp
@@ -1212,9 +1212,9 @@ bool CarlaEngine::isOscBridgeRegistered() const
 }
 #endif
 
-bool CarlaEngine::idleOsc()
+void CarlaEngine::idleOsc()
 {
-    return m_osc.idle();
+    m_osc.idle();
 }
 
 const char* CarlaEngine::getOscServerPathTCP() const
diff --git a/c++/carla-engine/carla_engine.hpp b/c++/carla-engine/carla_engine.hpp
index 433ea9a..2cb5b93 100644
--- a/c++/carla-engine/carla_engine.hpp
+++ b/c++/carla-engine/carla_engine.hpp
@@ -769,7 +769,7 @@ public:
     /*!
      * Idle OSC.
      */
-    bool idleOsc();
+    void idleOsc();
 
     /*!
      * Get OSC TCP server path.
diff --git a/c++/carla-engine/carla_engine_osc.cpp b/c++/carla-engine/carla_engine_osc.cpp
index db78192..0adc6fe 100644
--- a/c++/carla-engine/carla_engine_osc.cpp
+++ b/c++/carla-engine/carla_engine_osc.cpp
@@ -94,23 +94,17 @@ void CarlaEngineOsc::init(const char* const name)
     }
 }
 
-bool CarlaEngineOsc::idle()
+void CarlaEngineOsc::idle()
 {
-    bool msgReceived = false;
-
     if (m_serverTCP)
     {
-        while (lo_server_recv_noblock(m_serverTCP, 25) != 0)
-            msgReceived = true;
+        while (lo_server_recv_noblock(m_serverTCP, 0) != 0) {}
     }
 
     if (m_serverUDP)
     {
-        while (lo_server_recv_noblock(m_serverUDP, 25) != 0)
-            msgReceived = true;
+        while (lo_server_recv_noblock(m_serverUDP, 0) != 0) {}
     }
-
-    return !msgReceived;
 }
 
 void CarlaEngineOsc::close()
diff --git a/c++/carla-engine/carla_engine_osc.hpp b/c++/carla-engine/carla_engine_osc.hpp
index 12034ee..625713b 100644
--- a/c++/carla-engine/carla_engine_osc.hpp
+++ b/c++/carla-engine/carla_engine_osc.hpp
@@ -60,7 +60,7 @@ public:
     ~CarlaEngineOsc();
 
     void init(const char* const name);
-    bool idle();
+    void idle();
     void close();
 
     // -------------------------------------------------------------------
diff --git a/c++/carla-engine/carla_engine_thread.cpp b/c++/carla-engine/carla_engine_thread.cpp
index 701c1a3..bd07d65 100644
--- a/c++/carla-engine/carla_engine_thread.cpp
+++ b/c++/carla-engine/carla_engine_thread.cpp
@@ -143,8 +143,8 @@ void CarlaEngineThread::run()
             }
         }
 
-        if (! engine->idleOsc())
-            msleep(50);
+        engine->idleOsc();
+        msleep(oscRegisted ? 40 : 50);
     }
 }