diff --git a/mainwindow.cpp b/mainwindow.cpp
index 7ff8fc31c..ad6aab62d 100644
--- a/mainwindow.cpp
+++ b/mainwindow.cpp
@@ -253,12 +253,14 @@ void MainWindow::editMenu_About_To_Be_Shown() {
 void MainWindow::on_action_Undo_triggered()
 {
     undo_stack.undo();
+    editMenu_About_To_Be_Shown();
     panel_timeline->redraw_all_clips(true);
 }
 
 void MainWindow::on_action_Redo_triggered()
 {
     undo_stack.redo();
+    editMenu_About_To_Be_Shown();
     panel_timeline->redraw_all_clips(true);
 }
 
@@ -478,7 +480,7 @@ void MainWindow::on_actionGo_to_Next_Cut_triggered()
 void MainWindow::on_actionPreferences_triggered()
 {
     PreferencesDialog pd(this);
-    pd.setup_kbd_shortcuts(this->menuBar());
+    pd.setup_kbd_shortcuts(menuBar());
     pd.exec();
 }
 
diff --git a/mainwindow.ui b/mainwindow.ui
index 7e0f78bf4..f5bdadc25 100644
--- a/mainwindow.ui
+++ b/mainwindow.ui
@@ -24,7 +24,7 @@
      <x>0</x>
      <y>0</y>
      <width>653</width>
-     <height>29</height>
+     <height>17</height>
     </rect>
    </property>
    <widget class="QMenu" name="menu_File">
@@ -223,7 +223,7 @@
     <string>&amp;Redo</string>
    </property>
    <property name="shortcut">
-    <string>Ctrl+Shift+Z, Ctrl+Y</string>
+    <string>Ctrl+Shift+Z</string>
    </property>
   </action>
   <action name="actionCu_t">
diff --git a/project/clip.cpp b/project/clip.cpp
index e435c04a4..1f7fc3513 100644
--- a/project/clip.cpp
+++ b/project/clip.cpp
@@ -77,17 +77,18 @@ void Clip::reset() {
 	codecCtx = NULL;
 	texture = NULL;
 	cache_A.frames = NULL;
-	cache_B.frames = NULL;
+    cache_B.frames = NULL;
 }
 
 Clip::~Clip() {
     if (open) {
 		close_clip(this);
-	}
 
-    // make sure clip has closed before clip is destroyed
-    open_lock.lock();
-	open_lock.unlock();
+        // make sure clip has closed before clip is destroyed
+        if (multithreaded) {
+            cacher->wait();
+        }
+    }
 
     if (opening_transition != NULL) delete opening_transition;
     if (closing_transition != NULL) delete closing_transition;
diff --git a/ui/viewerwidget.cpp b/ui/viewerwidget.cpp
index b72309ff0..dc20761ad 100644
--- a/ui/viewerwidget.cpp
+++ b/ui/viewerwidget.cpp
@@ -30,7 +30,6 @@ ViewerWidget::ViewerWidget(QWidget *parent) : QOpenGLWidget(parent) {
 	setFormat(format);
 
     // start audio sending thread
-    connect(&audio_sender_thread, SIGNAL(finished()), &audio_sender_thread, SLOT(deleteLater()));
     audio_sender_thread.start();
 
     // error handler - retries after 250ms if we couldn't get the entire image
@@ -41,8 +40,7 @@ ViewerWidget::ViewerWidget(QWidget *parent) : QOpenGLWidget(parent) {
 ViewerWidget::~ViewerWidget() {
     audio_sender_thread.close = true;
     audio_sender_thread.cond.wakeAll();
-    audio_sender_thread.lock.lock();
-    audio_sender_thread.lock.unlock();
+    audio_sender_thread.wait();
 }
 
 void ViewerWidget::deleteFunction() {
@@ -234,27 +232,29 @@ void ViewerWidget::paintGL() {
 }
 
 AudioSenderThread::AudioSenderThread() : close(false) {
-    lock.lock();
-}
-
-AudioSenderThread::~AudioSenderThread() {
-    lock.unlock();
+    connect(this, SIGNAL(finished()), this, SLOT(deleteLater()));
 }
 
 void AudioSenderThread::run() {
+    lock.lock();
     while (true) {
         cond.wait(&lock);
         if (close) {
             break;
         } else {
+            int written_bytes = 0;
+
             int adjusted_read_index = audio_ibuffer_read%audio_ibuffer_size;
             int max_write = audio_ibuffer_size - adjusted_read_index;
-            if (send_audio_to_output(adjusted_read_index, max_write) == max_write) {
+            int actual_write = send_audio_to_output(adjusted_read_index, max_write);
+            written_bytes += actual_write;
+            if (actual_write == max_write) {
                 // got all the bytes, write again
-                send_audio_to_output(0, audio_ibuffer_size);
+                written_bytes += send_audio_to_output(0, audio_ibuffer_size);
             }
         }
     }
+    lock.unlock();
 }
 
 int AudioSenderThread::send_audio_to_output(int offset, int max) {
diff --git a/ui/viewerwidget.h b/ui/viewerwidget.h
index 2acf6de94..8ba9c6a49 100644
--- a/ui/viewerwidget.h
+++ b/ui/viewerwidget.h
@@ -16,7 +16,6 @@ struct Sequence;
 class AudioSenderThread : public QThread {
 public:
     AudioSenderThread();
-    ~AudioSenderThread();
     void run();
     QWaitCondition cond;
     bool close;