diff --git a/external/rtaudio/RtAudio.cpp b/external/rtaudio/RtAudio.cpp
index 6ad1eb5..ddd8ff3 100644
--- a/external/rtaudio/RtAudio.cpp
+++ b/external/rtaudio/RtAudio.cpp
@@ -180,7 +180,7 @@ RtAudio :: RtAudio( RtAudio::Api api )
   getCompiledApi( apis );
   for ( unsigned int i=0; i<apis.size(); i++ ) {
     openRtApi( apis[i] );
-    if ( rtapi_->getDeviceCount() ) break;
+    if ( rtapi_ && rtapi_->getDeviceCount() ) break;
   }
 
   if ( rtapi_ ) return;
diff --git a/src/AppFrame.cpp b/src/AppFrame.cpp
index c55e61c..6532d0a 100644
--- a/src/AppFrame.cpp
+++ b/src/AppFrame.cpp
@@ -45,7 +45,6 @@ AppFrame::AppFrame() :
 #endif
 
     wxBoxSizer *vbox = new wxBoxSizer(wxVERTICAL);
-    wxBoxSizer *demodOpts = new wxBoxSizer(wxVERTICAL);
     wxBoxSizer *demodVisuals = new wxBoxSizer(wxVERTICAL);
     wxBoxSizer *demodTray = new wxBoxSizer(wxHORIZONTAL);
     wxBoxSizer *demodScopeTray = new wxBoxSizer(wxVERTICAL);
diff --git a/src/audio/AudioThread.h b/src/audio/AudioThread.h
index 0d10f97..7adfa6f 100644
--- a/src/audio/AudioThread.h
+++ b/src/audio/AudioThread.h
@@ -18,6 +18,7 @@ public:
     int channels;
     float peak;
     std::vector<float> data;
+    std::mutex busy_update;
 
     AudioThreadInput() :
             frequency(0), sampleRate(0), channels(0), peak(0) {
diff --git a/src/demod/DemodDefs.h b/src/demod/DemodDefs.h
index 6282ac0..5f3e3fb 100644
--- a/src/demod/DemodDefs.h
+++ b/src/demod/DemodDefs.h
@@ -61,6 +61,7 @@ public:
     long long frequency;
     long long sampleRate;
     std::vector<liquid_float_complex> data;
+    std::mutex busy_rw;
 
     DemodulatorThreadIQData() :
             frequency(0), sampleRate(0) {
diff --git a/src/demod/DemodulatorThread.cpp b/src/demod/DemodulatorThread.cpp
index a14f8e2..57031e5 100644
--- a/src/demod/DemodulatorThread.cpp
+++ b/src/demod/DemodulatorThread.cpp
@@ -310,6 +310,8 @@ void DemodulatorThread::threadMain() {
 
         if (ati && audioVisOutputQueue != NULL && audioVisOutputQueue->empty()) {
 
+            ati_vis->busy_update.lock();
+
             int num_vis = DEMOD_VIS_SIZE;
             if (stereo) {
                 ati_vis->channels = 2;
@@ -342,6 +344,8 @@ void DemodulatorThread::threadMain() {
 //            std::cout << "Signal: " << agc_crcf_get_signal_level(agc) << " -- " << agc_crcf_get_rssi(agc) << "dB " << std::endl;
             }
 
+            ati_vis->busy_update.unlock();
+
             audioVisOutputQueue->push(ati_vis);
         }
         if (!threadQueueControl->empty()) {
diff --git a/src/sdr/SDRPostThread.cpp b/src/sdr/SDRPostThread.cpp
index 43839cb..9b5ab71 100644
--- a/src/sdr/SDRPostThread.cpp
+++ b/src/sdr/SDRPostThread.cpp
@@ -111,6 +111,9 @@ void SDRPostThread::threadMain() {
             }
 
             if (iqVisualQueue.load() != NULL && iqVisualQueue.load()->empty()) {
+
+                visualDataOut->busy_rw.lock();
+
                 if (visualDataOut->data.size() < num_vis_samples) {
                     if (visualDataOut->data.capacity() < num_vis_samples) {
                         visualDataOut->data.reserve(num_vis_samples);
@@ -121,6 +124,9 @@ void SDRPostThread::threadMain() {
                 visualDataOut->frequency = data_in->frequency;
                 visualDataOut->sampleRate = data_in->sampleRate;
                 visualDataOut->data.assign(dataOut.begin(), dataOut.begin() + num_vis_samples);
+
+                visualDataOut->busy_rw.unlock();
+
                 iqVisualQueue.load()->push(visualDataOut);
             }
 
diff --git a/src/util/DataTree.cpp b/src/util/DataTree.cpp
index 2f54cfa..1a17ec7 100755
--- a/src/util/DataTree.cpp
+++ b/src/util/DataTree.cpp
@@ -38,7 +38,7 @@ DataElement::DataElement() : data_type(DATA_NULL), data_val(NULL), data_size(0),
 
 DataElement::~DataElement() {
     if (data_val) {
-        delete data_val;
+        delete[] data_val;
         data_val = NULL;
     }
 }
@@ -1309,9 +1309,9 @@ long DataTree::getSerialized(char **ser_str, bool debug) {
         memcpy(data_out + data_ptr, element_serialized, element_serialized_size);
         data_ptr += element_serialized_size;
 
-        delete de_name_index_serialized;
-        delete de_num_children_serialized;
-        delete element_serialized;
+        delete[] de_name_index_serialized;
+        delete[] de_num_children_serialized;
+        delete[] element_serialized;
 
         /* if it has children, traverse into them */
         if (dn_stack.top()->hasAnother()) {
@@ -1360,8 +1360,8 @@ void DataTree::setSerialized(char *ser_str, bool debug) {
 
     /* unserialization is a little less straightforward since we have to do a countdown of remaining children */
     while (!dn_stack.empty()) {
-        int name_index;
-        int num_children;
+        int name_index = 0;
+        int num_children = 0;
 
         /* pull the index of the name of this node */
         de_name_index.setSerialized(ser_str + data_ptr);
@@ -1389,7 +1389,7 @@ void DataTree::setSerialized(char *ser_str, bool debug) {
         /* end debug output */
 
         /* name index >= 1 means it has a name */
-        if (name_index) {
+        if (name_index >= 1) {
             dn_stack.top()->setName(node_names[name_index - 1].c_str());
 
         } else /* name is nil */
@@ -1568,10 +1568,10 @@ bool DataTree::SaveToFile(const std::string& filename, bool compress, int compre
     fout << flush;
     fout.close();
 
-    delete hdr_serialized;
+    free(hdr_serialized);
 
     if (!compress) {
-        delete serialized;
+        free(serialized);
     } else {
         delete compressed;
     }
@@ -1630,8 +1630,8 @@ bool DataTree::LoadFromFile(const std::string& filename) {
 
     setSerialized(serialized);
 
-    delete serialized;
-    delete hdr_serialized;
+    delete[] serialized;
+    delete[] hdr_serialized;
 
     return true;
 }
diff --git a/src/visual/ModeSelectorCanvas.cpp b/src/visual/ModeSelectorCanvas.cpp
index 8c16e5b..04bd0c1 100644
--- a/src/visual/ModeSelectorCanvas.cpp
+++ b/src/visual/ModeSelectorCanvas.cpp
@@ -59,13 +59,6 @@ void ModeSelectorCanvas::OnPaint(wxPaintEvent& WXUNUSED(event)) {
 
     glContext->DrawBegin();
 
-    DemodulatorInstance *demod = wxGetApp().getDemodMgr().getLastActiveDemodulator();
-
-    int demodType = 0;
-    if (demod) {
-        demodType = demod->getDemodulatorType();
-    }
-
     int yval = getHoveredSelection();
 
     for (int i = 0; i < numChoices; i++) {
diff --git a/src/visual/PrimaryGLContext.cpp b/src/visual/PrimaryGLContext.cpp
index 74a406a..427f436 100644
--- a/src/visual/PrimaryGLContext.cpp
+++ b/src/visual/PrimaryGLContext.cpp
@@ -151,8 +151,6 @@ void PrimaryGLContext::DrawDemodInfo(DemodulatorInstance *demod, RGBColor color,
     glEnd();
 
     if (ofs * 2.0 < 16.0 / viewWidth) {
-        ofs = 16.0 / viewWidth;
-
         glColor4f(color.r, color.g, color.b, 0.2);
         glBegin(GL_QUADS);
         glVertex3f(uxPos - ofsLeft, hPos + labelHeight, 0.0);
@@ -241,8 +239,8 @@ void PrimaryGLContext::DrawDemod(DemodulatorInstance *demod, RGBColor color, lon
 
     glEnable(GL_BLEND);
 
-    std::string demodStr;
-    GLFont::Align demodAlign;
+    std::string demodStr = "";
+    GLFont::Align demodAlign = GLFont::GLFONT_ALIGN_CENTER;
 
     switch (demod->getDemodulatorType()) {
     case DEMOD_TYPE_FM:
diff --git a/src/visual/ScopeCanvas.cpp b/src/visual/ScopeCanvas.cpp
index 2b01de8..c80cc54 100644
--- a/src/visual/ScopeCanvas.cpp
+++ b/src/visual/ScopeCanvas.cpp
@@ -61,16 +61,23 @@ void ScopeCanvas::OnPaint(wxPaintEvent& WXUNUSED(event)) {
     if (!wxGetApp().getAudioVisualQueue()->empty()) {
         AudioThreadInput *demodAudioData;
         wxGetApp().getAudioVisualQueue()->pop(demodAudioData);
-        if (demodAudioData && demodAudioData->data.size()) {
-            if (waveform_points.size() != demodAudioData->data.size() * 2) {
-                waveform_points.resize(demodAudioData->data.size() * 2);
+
+        int iMax = demodAudioData?demodAudioData->data.size():0;
+
+        if (demodAudioData && iMax) {
+            if (waveform_points.size() != iMax * 2) {
+                waveform_points.resize(iMax * 2);
             }
 
-            for (int i = 0, iMax = demodAudioData->data.size(); i < iMax; i++) {
+            demodAudioData->busy_update.lock();
+
+            for (int i = 0; i < iMax; i++) {
                 waveform_points[i * 2 + 1] = demodAudioData->data[i] * 0.5f;
                 waveform_points[i * 2] = ((double) i / (double) iMax);
             }
 
+            demodAudioData->busy_update.unlock();
+
             setStereo(demodAudioData->channels == 2);
         } else {
             std::cout << "Incoming Demodulator data empty?" << std::endl;
diff --git a/src/visual/TuningCanvas.cpp b/src/visual/TuningCanvas.cpp
index 375c2d5..273fbf0 100644
--- a/src/visual/TuningCanvas.cpp
+++ b/src/visual/TuningCanvas.cpp
@@ -328,12 +328,6 @@ void TuningCanvas::OnMouseWheelMoved(wxMouseEvent& event) {
 }
 
 void TuningCanvas::OnMouseReleased(wxMouseEvent& event) {
-    GLint vp[4];
-    glGetIntegerv( GL_VIEWPORT, vp);
-
-    float viewHeight = (float) vp[3];
-    float viewWidth = (float) vp[2];
-
     InteractiveCanvas::OnMouseReleased(event);
 
     int hExponent = hoverIndex - 1;
diff --git a/src/visual/TuningContext.cpp b/src/visual/TuningContext.cpp
index 16d49ac..8d1bdba 100644
--- a/src/visual/TuningContext.cpp
+++ b/src/visual/TuningContext.cpp
@@ -69,7 +69,6 @@ void TuningContext::DrawTuner(long long freq, int count, float displayPos, float
     glGetIntegerv( GL_VIEWPORT, vp);
 
     float viewHeight = (float) vp[3];
-    float viewWidth = (float) vp[2];
 
     freqStr.str("");
     freqStr << freq;
@@ -118,8 +117,6 @@ void TuningContext::DrawTunerDigitBox(int index, int count, float displayPos, fl
     glGetIntegerv( GL_VIEWPORT, vp);
 
     float viewHeight = (float) vp[3];
-    float viewWidth = (float) vp[2];
-
     float pixelHeight = 2.0/viewHeight;
 
     glColor4f(1.0, 0,0,1);
@@ -187,12 +184,6 @@ bool bottom) {
 }
 
 void TuningContext::DrawDemodFreqBw(long long freq, unsigned int bw, long long center) {
-    GLint vp[4];
-    glGetIntegerv( GL_VIEWPORT, vp);
-
-    float viewHeight = (float) vp[3];
-    float viewWidth = (float) vp[2];
-
     DrawTuner(freq, 11, -1.0, (1.0 / 3.0) * 2.0);
     DrawTuner(bw, 7, -1.0 + (2.25 / 3.0), (1.0 / 4.0) * 2.0);
     DrawTuner(center, 11, -1.0 + (2.0 / 3.0) * 2.0, (1.0 / 3.0) * 2.0);
diff --git a/src/visual/WaterfallCanvas.cpp b/src/visual/WaterfallCanvas.cpp
index c504dcf..59f7c21 100644
--- a/src/visual/WaterfallCanvas.cpp
+++ b/src/visual/WaterfallCanvas.cpp
@@ -110,6 +110,8 @@ void WaterfallCanvas::OnPaint(wxPaintEvent& WXUNUSED(event)) {
         DemodulatorThreadIQData *iqData;
         wxGetApp().getIQVisualQueue()->pop(iqData);
 
+        iqData->busy_rw.lock();
+
         if (iqData && iqData->data.size()) {
             setData(iqData);
             if (otherWaterfallCanvas) {
@@ -118,6 +120,8 @@ void WaterfallCanvas::OnPaint(wxPaintEvent& WXUNUSED(event)) {
         } else {
             std::cout << "Incoming IQ data empty?" << std::endl;
         }
+
+        iqData->busy_rw.unlock();
     }
 
     glContext->SetCurrent(*this);
@@ -362,14 +366,12 @@ void WaterfallCanvas::setData(DemodulatorThreadIQData *input) {
                 bw = getBandwidth();
                 bw = (long long) ceil((long double) bw * currentZoom);
                 if (bw >= wxGetApp().getSampleRate()) {
-                    bw = wxGetApp().getSampleRate();
                     disableView();
                     if (spectrumCanvas) {
                         spectrumCanvas->disableView();
                     }
                 } else {
                     if (mouseTracker.mouseInView()) {
-                        long long freq = wxGetApp().getFrequency();
                         long long mfreqA = getFrequencyAt(mouseTracker.getMouseX());
                         setBandwidth(bw);
                         long long mfreqB = getFrequencyAt(mouseTracker.getMouseX());
@@ -517,8 +519,7 @@ void WaterfallCanvas::setData(DemodulatorThreadIQData *input) {
 
         } else {
             if (last_data_size + num_written < fft_size) { // priming
-                unsigned int num_copy = fft_size;
-                num_copy = fft_size - last_data_size;
+                unsigned int num_copy = fft_size - last_data_size;
                 if (num_written > num_copy) {
                     num_copy = num_written;
                 }
diff --git a/src/visual/WaterfallContext.cpp b/src/visual/WaterfallContext.cpp
index f28a818..3ff3e30 100644
--- a/src/visual/WaterfallContext.cpp
+++ b/src/visual/WaterfallContext.cpp
@@ -13,8 +13,6 @@ void WaterfallContext::Setup(int fft_size_in, int num_waterfall_lines_in) {
     waterfall_lines = num_waterfall_lines_in;
     fft_size = fft_size_in;
 
-    int half_fft_size = fft_size / 2;
-
     for (int i = 0; i < 2; i++) {
         if (waterfall[i]) {
             glDeleteTextures(1, &waterfall[i]);
@@ -23,7 +21,6 @@ void WaterfallContext::Setup(int fft_size_in, int num_waterfall_lines_in) {
 
         waterfall_ofs[i] = waterfall_lines - 1;
     }
-    // Stagger memory updates at half intervals for tiles
 }
 
 void WaterfallContext::refreshTheme() {
@@ -72,7 +69,7 @@ void WaterfallContext::Draw(std::vector<float> &points) {
 		}
 		waterfall_slice = new unsigned char[half_fft_size];
 
-        delete waterfall_tex;
+        delete[] waterfall_tex;
     }
 
     if (activeTheme != ThemeMgr::mgr.currentTheme) {
@@ -107,7 +104,6 @@ void WaterfallContext::Draw(std::vector<float> &points) {
     glGetIntegerv(GL_VIEWPORT, vp);
 
     float viewWidth = (float) vp[2];
-    float viewHeight = (float) vp[3];
 
     // some bias to prevent seams at odd scales
     float half_pixel = 1.0 / viewWidth;