diff --git a/c++/carla-bridge/carla_bridge_client.cpp b/c++/carla-bridge/carla_bridge_client.cpp
index 0cefbdf..926f3e0 100644
--- a/c++/carla-bridge/carla_bridge_client.cpp
+++ b/c++/carla-bridge/carla_bridge_client.cpp
@@ -60,10 +60,10 @@ CarlaBridgeClient::~CarlaBridgeClient()
 #endif
 }
 
+#ifdef BUILD_BRIDGE_UI
 // ---------------------------------------------------------------------
 // ui initialization
 
-#ifdef BUILD_BRIDGE_UI
 bool CarlaBridgeClient::init(const char* const, const char* const)
 {
     qDebug("CarlaBridgeClient::init()");
@@ -131,7 +131,7 @@ void CarlaBridgeClient::sendOscUpdate()
     qDebug("CarlaBridgeClient::sendOscUpdate()");
     CARLA_ASSERT(m_oscData);
 
-    if (m_oscData->target)
+    if (m_oscData && m_oscData->target)
         osc_send_update(m_oscData, m_osc.getServerPath());
 }
 
@@ -142,7 +142,7 @@ void CarlaBridgeClient::sendOscBridgeError(const char* const error)
     CARLA_ASSERT(m_oscData);
     CARLA_ASSERT(error);
 
-    if (m_oscData->target)
+    if (m_oscData && m_oscData->target)
         osc_send_bridge_error(m_oscData, error);
 }
 
@@ -201,7 +201,7 @@ void CarlaBridgeClient::sendOscConfigure(const char* const key, const char* cons
     qDebug("CarlaBridgeClient::sendOscConfigure(\"%s\", \"%s\")", key, value);
     CARLA_ASSERT(m_oscData);
 
-    if (m_oscData->target)
+    if (m_oscData && m_oscData->target)
         osc_send_configure(m_oscData, key, value);
 }
 
@@ -210,7 +210,7 @@ void CarlaBridgeClient::sendOscControl(const int32_t index, const float value)
     qDebug("CarlaBridgeClient::sendOscControl(%i, %f)", index, value);
     CARLA_ASSERT(m_oscData);
 
-    if (m_oscData->target)
+    if (m_oscData && m_oscData->target)
         osc_send_control(m_oscData, index, value);
 }
 
@@ -219,7 +219,7 @@ void CarlaBridgeClient::sendOscProgram(const int32_t index)
     qDebug("CarlaBridgeClient::sendOscProgram(%i)", index);
     CARLA_ASSERT(m_oscData);
 
-    if (m_oscData->target)
+    if (m_oscData && m_oscData->target)
         osc_send_program(m_oscData, index);
 }
 
@@ -228,7 +228,7 @@ void CarlaBridgeClient::sendOscMidiProgram(const int32_t index)
     qDebug("CarlaBridgeClient::sendOscMidiProgram(%i)", index);
     CARLA_ASSERT(m_oscData);
 
-    if (m_oscData->target)
+    if (m_oscData && m_oscData->target)
         osc_send_midi_program(m_oscData, index);
 }
 
@@ -237,7 +237,7 @@ void CarlaBridgeClient::sendOscMidi(const uint8_t midiBuf[4])
     qDebug("CarlaBridgeClient::sendOscMidi(%p)", midiBuf);
     CARLA_ASSERT(m_oscData);
 
-    if (m_oscData->target)
+    if (m_oscData && m_oscData->target)
         osc_send_midi(m_oscData, midiBuf);
 }
 
@@ -246,7 +246,7 @@ void CarlaBridgeClient::sendOscExiting()
     qDebug("CarlaBridgeClient::sendOscExiting()");
     CARLA_ASSERT(m_oscData);
 
-    if (m_oscData->target)
+    if (m_oscData && m_oscData->target)
         osc_send_exiting(m_oscData);
 }
 
@@ -257,7 +257,7 @@ void CarlaBridgeClient::sendOscBridgeUpdate()
     CARLA_ASSERT(m_oscData);
     CARLA_ASSERT(m_oscData->target && m_osc.m_serverPath);
 
-    if (m_oscData->target && m_osc.m_serverPath)
+    if (m_oscData && m_oscData->target && m_osc.m_serverPath)
         osc_send_bridge_update(m_oscData, m_osc.m_serverPath);
 }
 #endif
@@ -268,7 +268,7 @@ void CarlaBridgeClient::sendOscLv2TransferAtom(const int32_t portIndex, const ch
     qDebug("CarlaBridgeClient::sendOscLv2TransferAtom(%i, \"%s\", \"%s\")", portIndex, typeStr, atomBuf);
     CARLA_ASSERT(m_oscData);
 
-    if (m_oscData->target)
+    if (m_oscData && m_oscData->target)
         osc_send_lv2_transfer_atom(m_oscData, portIndex, typeStr, atomBuf);
 }
 
@@ -277,7 +277,7 @@ void CarlaBridgeClient::sendOscLv2TransferEvent(const int32_t portIndex, const c
     qDebug("CarlaBridgeClient::sendOscLv2TransferEvent(%i, \"%s\", \"%s\")", portIndex, typeStr, atomBuf);
     CARLA_ASSERT(m_oscData);
 
-    if (m_oscData->target)
+    if (m_oscData && m_oscData->target)
         osc_send_lv2_transfer_event(m_oscData, portIndex, typeStr, atomBuf);
 }
 #endif
diff --git a/c++/carla-bridge/carla_bridge_ui-lv2.cpp b/c++/carla-bridge/carla_bridge_ui-lv2.cpp
index 7028f9e..576b21a 100644
--- a/c++/carla-bridge/carla_bridge_ui-lv2.cpp
+++ b/c++/carla-bridge/carla_bridge_ui-lv2.cpp
@@ -559,7 +559,7 @@ public:
         CARLA_ASSERT(portIndex >= 0);
         CARLA_ASSERT(atom);
 
-        if (handle && descriptor && descriptor->port_event)
+        if (atom && handle && descriptor && descriptor->port_event)
             descriptor->port_event(handle, portIndex, atom->size, CARLA_URI_MAP_ID_ATOM_TRANSFER_ATOM, atom);
     }
 
@@ -569,7 +569,7 @@ public:
         CARLA_ASSERT(portIndex >= 0);
         CARLA_ASSERT(atom);
 
-        if (handle && descriptor && descriptor->port_event)
+        if (atom && handle && descriptor && descriptor->port_event)
             descriptor->port_event(handle, portIndex, atom->size, CARLA_URI_MAP_ID_ATOM_TRANSFER_EVENT, atom);
 #if 0
         if (handle && descriptor && descriptor->port_event)
@@ -654,6 +654,9 @@ public:
 
     void handleUiWrite(uint32_t portIndex, uint32_t bufferSize, uint32_t format, const void* buffer)
     {
+        if (! buffer)
+            return;
+
         if (format == 0)
         {
             CARLA_ASSERT(buffer);
diff --git a/c++/carla-bridge/qtcreator/carla-bridge-lv2-gtk2.pro b/c++/carla-bridge/qtcreator/carla-bridge-lv2-gtk2.pro
index f332305..1ac275b 100644
--- a/c++/carla-bridge/qtcreator/carla-bridge-lv2-gtk2.pro
+++ b/c++/carla-bridge/qtcreator/carla-bridge-lv2-gtk2.pro
@@ -10,9 +10,11 @@ TEMPLATE = app
 VERSION  = 0.5.0
 
 SOURCES = \
+    ../carla_bridge_client.cpp \
     ../carla_bridge_osc.cpp \
-    ../carla_bridge_ui-lv2.cpp \
-    ../carla_bridge_toolkit-gtk.cpp
+    ../carla_bridge_toolkit.cpp \
+    ../carla_bridge_toolkit-gtk.cpp \
+    ../carla_bridge_ui-lv2.cpp
 
 HEADERS = \
     ../carla_bridge.hpp \
@@ -36,6 +38,6 @@ LIBS    = \
 
 DEFINES  = QTCREATOR_TEST
 DEFINES += DEBUG
-DEFINES += BUILD_BRIDGE BUILD_BRIDGE_UI BRIDGE_LV2 BRIDGE_LV2_GTK2
+DEFINES += BUILD_BRIDGE BUILD_BRIDGE_UI BRIDGE_LV2 BRIDGE_GTK2 BRIDGE_LV2_GTK2
 
 QMAKE_CXXFLAGS *= -std=c++0x
diff --git a/c++/carla-bridge/qtcreator/carla-bridge-lv2-gtk3.pro b/c++/carla-bridge/qtcreator/carla-bridge-lv2-gtk3.pro
index 9ce3c58..990398b 100644
--- a/c++/carla-bridge/qtcreator/carla-bridge-lv2-gtk3.pro
+++ b/c++/carla-bridge/qtcreator/carla-bridge-lv2-gtk3.pro
@@ -10,9 +10,11 @@ TEMPLATE = app
 VERSION  = 0.5.0
 
 SOURCES = \
+    ../carla_bridge_client.cpp \
     ../carla_bridge_osc.cpp \
-    ../carla_bridge_ui-lv2.cpp \
-    ../carla_bridge_toolkit-gtk.cpp
+    ../carla_bridge_toolkit.cpp \
+    ../carla_bridge_toolkit-gtk.cpp \
+    ../carla_bridge_ui-lv2.cpp
 
 HEADERS = \
     ../carla_bridge.hpp \
@@ -27,7 +29,8 @@ HEADERS = \
     ../../carla-utils/carla_lv2_utils.hpp
 
 INCLUDEPATH = .. \
-    ../../carla-includes
+    ../../carla-includes \
+    ../../carla-utils
 
 LIBS    = \
     ../../carla-lilv/carla_lilv.a \
@@ -35,6 +38,6 @@ LIBS    = \
 
 DEFINES  = QTCREATOR_TEST
 DEFINES += DEBUG
-DEFINES += BUILD_BRIDGE BUILD_BRIDGE_UI BRIDGE_LV2 BRIDGE_LV2_GTK3
+DEFINES += BUILD_BRIDGE BUILD_BRIDGE_UI BRIDGE_LV2 BRIDGE_GTK3 BRIDGE_LV2_GTK3
 
 QMAKE_CXXFLAGS *= -std=c++0x
diff --git a/c++/carla-bridge/qtcreator/carla-bridge-lv2-qt4.pro b/c++/carla-bridge/qtcreator/carla-bridge-lv2-qt4.pro
index 33936be..c22d0bf 100644
--- a/c++/carla-bridge/qtcreator/carla-bridge-lv2-qt4.pro
+++ b/c++/carla-bridge/qtcreator/carla-bridge-lv2-qt4.pro
@@ -10,9 +10,11 @@ TEMPLATE = app
 VERSION  = 0.5.0
 
 SOURCES = \
+    ../carla_bridge_client.cpp \
     ../carla_bridge_osc.cpp \
-    ../carla_bridge_ui-lv2.cpp \
-    ../carla_bridge_toolkit-qt.cpp
+    ../carla_bridge_toolkit.cpp \
+    ../carla_bridge_toolkit-qt.cpp \
+    ../carla_bridge_ui-lv2.cpp
 
 HEADERS = \
     ../carla_bridge.hpp \
@@ -27,7 +29,8 @@ HEADERS = \
     ../../carla-utils/carla_lv2_utils.hpp
 
 INCLUDEPATH = .. \
-    ../../carla-includes
+    ../../carla-includes \
+    ../../carla-utils
 
 LIBS    = \
     ../../carla-lilv/carla_lilv.a \
@@ -35,6 +38,6 @@ LIBS    = \
 
 DEFINES  = QTCREATOR_TEST
 DEFINES += DEBUG
-DEFINES += BUILD_BRIDGE BUILD_BRIDGE_UI BRIDGE_LV2 BRIDGE_LV2_QT4
+DEFINES += BUILD_BRIDGE BUILD_BRIDGE_UI BRIDGE_LV2 BRIDGE_QT4 BRIDGE_LV2_QT4
 
 QMAKE_CXXFLAGS *= -std=c++0x
diff --git a/c++/carla-bridge/qtcreator/carla-bridge-lv2-qt5.pro b/c++/carla-bridge/qtcreator/carla-bridge-lv2-qt5.pro
index 300b47d..9b335a5 100644
--- a/c++/carla-bridge/qtcreator/carla-bridge-lv2-qt5.pro
+++ b/c++/carla-bridge/qtcreator/carla-bridge-lv2-qt5.pro
@@ -10,9 +10,11 @@ TEMPLATE = app
 VERSION  = 0.5.0
 
 SOURCES = \
+    ../carla_bridge_client.cpp \
     ../carla_bridge_osc.cpp \
-    ../carla_bridge_ui-lv2.cpp \
-    ../carla_bridge_toolkit-qt.cpp
+    ../carla_bridge_toolkit.cpp \
+    ../carla_bridge_toolkit-qt.cpp \
+    ../carla_bridge_ui-lv2.cpp
 
 HEADERS = \
     ../carla_bridge.hpp \
@@ -36,6 +38,6 @@ LIBS    = \
 
 DEFINES  = QTCREATOR_TEST
 DEFINES += DEBUG
-DEFINES += BUILD_BRIDGE BUILD_BRIDGE_UI BRIDGE_LV2 BRIDGE_LV2_QT5
+DEFINES += BUILD_BRIDGE BUILD_BRIDGE_UI BRIDGE_LV2 BRIDGE_QT5 BRIDGE_LV2_QT5
 
 QMAKE_CXXFLAGS *= -std=c++0x
diff --git a/c++/carla-bridge/qtcreator/carla-bridge-lv2-x11.pro b/c++/carla-bridge/qtcreator/carla-bridge-lv2-x11.pro
index 767732c..30d9697 100644
--- a/c++/carla-bridge/qtcreator/carla-bridge-lv2-x11.pro
+++ b/c++/carla-bridge/qtcreator/carla-bridge-lv2-x11.pro
@@ -1,6 +1,10 @@
 # QtCreator project file
 
+contains(QT_VERSION, ^5.*) {
+QT = core widgets
+} else {
 QT = core gui
+}
 
 CONFIG    = debug link_pkgconfig qt warn_on
 PKGCONFIG = liblo
@@ -10,9 +14,11 @@ TEMPLATE = app
 VERSION  = 0.5.0
 
 SOURCES = \
+    ../carla_bridge_client.cpp \
     ../carla_bridge_osc.cpp \
-    ../carla_bridge_ui-lv2.cpp \
-    ../carla_bridge_toolkit-qt.cpp
+    ../carla_bridge_toolkit.cpp \
+    ../carla_bridge_toolkit-qt.cpp \
+    ../carla_bridge_ui-lv2.cpp
 
 HEADERS = \
     ../carla_bridge.hpp \
@@ -27,9 +33,10 @@ HEADERS = \
     ../../carla-utils/carla_lv2_utils.hpp
 
 INCLUDEPATH = .. \
-    ../../carla-includes
+    ../../carla-includes \
+    ../../carla-utils
 
-LIBS    = \
+LIBS = \
     ../../carla-lilv/carla_lilv.a \
     ../../carla-rtmempool/carla_rtmempool.a