Don't allow program to quit whilst playing track.

app/musicmuster.py

@@ -85,6 +85,15 @@ class Window(QMainWindow, Ui_MainWindow):
                 track = add_path_to_db(fname)
                 self.playlist.add_to_playlist(track)
 
+    def closeEvent(self, event):
+        "Don't allow window to close when a track is playing"
+
+        if self.playlist.music.playing():
+            event.ignore()
+            # TODO notify user
+        else:
+            event.accept()
+
     def connect_signals_slots(self):
         self.actionAdd_file.triggered.connect(self.add_file)
         self.action_Clear_selection.triggered.connect(