MSP fixes

js/msp.js

@@ -108,13 +108,13 @@ var MSP = {
         });
     },
     listen: function(listener) {
-        if (this.listeners[0] == undefined) {
-            this.listeners[0] = listener;
-        }
-        else if (this.listeners.indexOf(listener) == -1) {
+        if (this.listeners.indexOf(listener) == -1) {
             this.listeners.push(listener);
         }
     },
+    clearListeners: function() {
+        this.listeners = [];  
+    },
     send_message: function (code, data, callback_sent, callback_msp) {
         var bufferOut,
             bufView;

js/msp/MSPHelper.js

@@ -683,6 +683,9 @@ MspHelper.prototype.process_data = function(dataHandler) {
             FILTER_CONFIG.yaw_lpf_hz = data.getUint16(offset, 1);
             break;
 
+        case MSPCodes.MSP_SET_PID_ADVANCED:
+            console.log("Advanced PID settings saved");
+            break;
         case MSPCodes.MSP_PID_ADVANCED:
             var offset = 0;
             if (semver.gte(CONFIG.flightControllerVersion, "3.0.0")) {

js/serial_backend.js

@@ -322,6 +322,8 @@ function onClosed(result) {
     
     var battery = $('#quad-status_wrapper');
     battery.hide();
+    
+    MSP.clearListeners();
 }
 
 function read_serial(info) {