Resolved two issues:

1) While in HMD mode -> open Tablet -> Click Desktop.  Desktop mode will be on.
2) Menu sync problem while switching modes.

interface/src/Application.cpp

@@ -1360,7 +1360,7 @@ Application::Application(int& argc, char** argv, QElapsedTimer& startupTimer, bo
 
         if (_autoSwitchDisplayModeSupportedHMDPlugin) {
             if (getActiveDisplayPlugin() != _autoSwitchDisplayModeSupportedHMDPlugin &&
-                !_autoSwitchDisplayModeSupportedHMDPlugin->isStandBySessionActive()) {
+                !_autoSwitchDisplayModeSupportedHMDPlugin->isSessionActive()) {
                     startHMDStandBySession();
             }
             // Poll periodically to check whether the user has worn HMD or not. Switch Display mode accordingly.
@@ -1602,8 +1602,8 @@ void Application::aboutToQuit() {
 
     getActiveDisplayPlugin()->deactivate();
     if (_autoSwitchDisplayModeSupportedHMDPlugin 
-        && _autoSwitchDisplayModeSupportedHMDPlugin->isStandBySessionActive()) {
-        _autoSwitchDisplayModeSupportedHMDPlugin->endStandBySession();
+        && _autoSwitchDisplayModeSupportedHMDPlugin->isSessionActive()) {
+        _autoSwitchDisplayModeSupportedHMDPlugin->endSession();
     }
     // use the CloseEventSender via a QThread to send an event that says the user asked for the app to close
     auto closeEventSender = DependencyManager::get<CloseEventSender>();
@@ -6827,13 +6827,14 @@ void Application::switchDisplayMode() {
         // Switch to respective mode as soon as currentHMDWornStatus changes
         if (currentHMDWornStatus) {
             qCDebug(interfaceapp) << "Switching from Desktop to HMD mode";
-            endHMDStandBySession();
+            endHMDSession();
             setActiveDisplayPlugin(_autoSwitchDisplayModeSupportedHMDPluginName);
         } else {
             qCDebug(interfaceapp) << "Switching from HMD to desktop mode";
             setActiveDisplayPlugin(DESKTOP_DISPLAY_PLUGIN_NAME);
             startHMDStandBySession();
         }
+        emit activeDisplayPluginChanged();
     }
     _previousHMDWornStatus = currentHMDWornStatus;
 }
@@ -6842,8 +6843,8 @@ void Application::startHMDStandBySession() {
     _autoSwitchDisplayModeSupportedHMDPlugin->startStandBySession();
 }
 
-void Application::endHMDStandBySession() {
-    _autoSwitchDisplayModeSupportedHMDPlugin->endStandBySession();
+void Application::endHMDSession() {
+    _autoSwitchDisplayModeSupportedHMDPlugin->endSession();
 }
 
 mat4 Application::getEyeProjection(int eye) const {

interface/src/Application.h

@@ -685,6 +685,6 @@ private:
     QString _autoSwitchDisplayModeSupportedHMDPluginName;
     bool _previousHMDWornStatus;
     void startHMDStandBySession();
-    void endHMDStandBySession();
+    void endHMDSession();
 };
 #endif // hifi_Application_h

libraries/display-plugins/src/display-plugins/OpenGLDisplayPlugin.cpp

@@ -346,9 +346,9 @@ bool OpenGLDisplayPlugin::startStandBySession() {
     return Parent::startStandBySession();
 }
 
-void OpenGLDisplayPlugin::endStandBySession() {
-    deactivateStandBySession();
-    Parent::endStandBySession();
+void OpenGLDisplayPlugin::endSession() {
+    deactivateSession();
+    Parent::endSession();
 }
 
 void OpenGLDisplayPlugin::customizeContext() {

libraries/display-plugins/src/display-plugins/OpenGLDisplayPlugin.h

@@ -43,7 +43,7 @@ public:
     bool activate() override final;
     void deactivate() override final;
     bool startStandBySession() override final;
-    void endStandBySession() override final;
+    void endSession() override final;
     bool eventFilter(QObject* receiver, QEvent* event) override;
     bool isDisplayVisible() const override { return true; }
 
@@ -104,7 +104,7 @@ protected:
 	
     // Returns true on successful activation of standby session
     virtual bool activateStandBySession() { return true; }
-    virtual void deactivateStandBySession() {}
+    virtual void deactivateSession() {}
 
     // Plugin specific functionality to send the composed scene to the output window or device
     virtual void internalPresent();

libraries/plugins/src/plugins/Plugin.h

@@ -54,16 +54,16 @@ public:
         return _active;
     }
     virtual bool startStandBySession() {
-        _standbysessionstatus = true;
-        return _standbysessionstatus;
+        _sessionStatus = true;
+        return _sessionStatus;
     }
 
-    virtual void endStandBySession() {
-        _standbysessionstatus = false;
+    virtual void endSession() {
+        _sessionStatus = false;
     }
 
-    virtual bool isStandBySessionActive() {
-        return _standbysessionstatus;
+    virtual bool isSessionActive() {
+        return _sessionStatus;
     }
 
     /**
@@ -85,7 +85,7 @@ signals:
 
 protected:
     bool _active { false };
-    bool _standbysessionstatus { false };
+    bool _sessionStatus { false };
     PluginContainer* _container { nullptr };
     static const char* UNKNOWN_PLUGIN_ID;
 

plugins/oculus/src/OculusBaseDisplayPlugin.cpp

@@ -123,8 +123,6 @@ bool OculusBaseDisplayPlugin::internalActivate() {
 
 void OculusBaseDisplayPlugin::internalDeactivate() {
     Parent::internalDeactivate();
-    releaseOculusSession();
-    _session = nullptr;
 }
 
 bool OculusBaseDisplayPlugin::activateStandBySession() {
@@ -134,7 +132,7 @@ bool OculusBaseDisplayPlugin::activateStandBySession() {
     }
     return true;
 }
-void OculusBaseDisplayPlugin::deactivateStandBySession() {
+void OculusBaseDisplayPlugin::deactivateSession() {
     releaseOculusSession();
     _session = nullptr;
 }

plugins/oculus/src/OculusBaseDisplayPlugin.h

@@ -35,7 +35,7 @@ protected:
     bool internalActivate() override;
     void internalDeactivate() override;
     bool activateStandBySession() override;
-    void deactivateStandBySession() override;
+    void deactivateSession() override;
     void updatePresentPose() override;
 
 protected: