From 2c9c07ccf5ae8fed672d029b6f6c29ca9e2bd144 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Jean-Fran=C3=A7ois=20Milants?= <jf@codingfield.com>
Date: Mon, 23 Oct 2023 20:12:34 +0200
Subject: [PATCH 1/5] Application selection at build time

A list of "user applications" is built at compile time. It contains all the info needed to create the application at runtime (ptr to a create() function) and to display the app in the application menu. All applications declare a TypeTrait with these information.
When a new app must be loaded, DisplayApp first check if this app is a System app (in which case it creates it like it did before). If it's not a System app, it looks for the app in the list of User applications and creates it if it found it.
Those changes allow to more easily add new app and to select which app must be built into the firmware.
Switch to C++20 (and fix a few issues in SpiMaster.cpp and Watchdog.cpp.
---
 CMakeLists.txt                             |   2 +-
 src/CMakeLists.txt                         |   1 -
 src/displayapp/Apps.h                      |  29 +++++-
 src/displayapp/Controllers.h               |  51 ++++++++++
 src/displayapp/DisplayApp.cpp              | 102 ++++++++++----------
 src/displayapp/DisplayApp.h                |   5 +
 src/displayapp/UserApps.h                  |  36 +++++++
 src/displayapp/screens/Alarm.cpp           |   4 +
 src/displayapp/screens/Alarm.h             |  26 +++--
 src/displayapp/screens/ApplicationList.cpp |  24 +++--
 src/displayapp/screens/ApplicationList.h   |  38 ++------
 src/displayapp/screens/Clock.h             |  11 ++-
 src/displayapp/screens/HeartRate.h         |   9 ++
 src/displayapp/screens/InfiniPaint.h       |  11 +++
 src/displayapp/screens/Metronome.h         |   9 ++
 src/displayapp/screens/Motion.h            |  10 ++
 src/displayapp/screens/Music.h             |  11 +++
 src/displayapp/screens/Navigation.h        |  11 +++
 src/displayapp/screens/Paddle.h            |  11 +++
 src/displayapp/screens/Steps.h             |  11 +++
 src/displayapp/screens/StopWatch.h         | 105 ++++++++++++---------
 src/displayapp/screens/Tile.cpp            |   1 -
 src/displayapp/screens/Timer.cpp           |   2 +-
 src/displayapp/screens/Timer.h             |  76 ++++++++-------
 src/displayapp/screens/Twos.h              |   9 +-
 src/displayapp/screens/Weather.h           |  13 ++-
 src/drivers/SpiMaster.cpp                  |  12 +--
 src/drivers/Watchdog.cpp                   |   2 +-
 src/systemtask/SystemTask.cpp              |   3 +
 29 files changed, 445 insertions(+), 190 deletions(-)
 create mode 100644 src/displayapp/Controllers.h
 create mode 100644 src/displayapp/UserApps.h

diff --git a/CMakeLists.txt b/CMakeLists.txt
index 83c6e98db8..41989489bc 100644
--- a/CMakeLists.txt
+++ b/CMakeLists.txt
@@ -5,7 +5,7 @@ set(CMAKE_BUILD_TYPE Release CACHE STRING "Choose Debug or Release")
 project(pinetime VERSION 1.13.0 LANGUAGES C CXX ASM)
 
 set(CMAKE_C_STANDARD 99)
-set(CMAKE_CXX_STANDARD 14)
+set(CMAKE_CXX_STANDARD 20)
 
 # set(CMAKE_GENERATOR "Unix Makefiles")
 set(CMAKE_C_EXTENSIONS OFF)
diff --git a/src/CMakeLists.txt b/src/CMakeLists.txt
index 8e8e96863b..dc718bab13 100644
--- a/src/CMakeLists.txt
+++ b/src/CMakeLists.txt
@@ -394,7 +394,6 @@ list(APPEND SOURCE_FILES
         displayapp/screens/Notifications.cpp
         displayapp/screens/Twos.cpp
         displayapp/screens/HeartRate.cpp
-        displayapp/screens/Motion.cpp
         displayapp/screens/FlashLight.cpp
         displayapp/screens/List.cpp
         displayapp/screens/CheckboxList.cpp
diff --git a/src/displayapp/Apps.h b/src/displayapp/Apps.h
index f253bc0387..d96e6ea721 100644
--- a/src/displayapp/Apps.h
+++ b/src/displayapp/Apps.h
@@ -1,5 +1,5 @@
 #pragma once
-
+#include <cstddef>
 namespace Pinetime {
   namespace Applications {
     enum class Apps {
@@ -37,7 +37,32 @@ namespace Pinetime {
       SettingChimes,
       SettingShakeThreshold,
       SettingBluetooth,
-      Error
+      Error,
+      Weather
+    };
+    template <Apps>
+    struct AppTraits {};
+
+    template<Apps ...As>
+    struct TypeList {
+      static constexpr size_t Count = sizeof...(As);
     };
+
+    using UserAppTypes = TypeList<Apps::Alarm,
+                                  Apps::HeartRate,
+                                  Apps::Paint,
+                                  Apps::Metronome,
+                                  Apps::Music,
+                                  Apps::Navigation,
+                                  Apps::Paddle,
+                                  Apps::Steps,
+                                  Apps::StopWatch,
+                                  Apps::Timer,
+                                  Apps::Twos
+                                  /*
+                                  Apps::Weather,
+                                  Apps::Motion
+                                  */
+                                  >;
   }
 }
diff --git a/src/displayapp/Controllers.h b/src/displayapp/Controllers.h
new file mode 100644
index 0000000000..cef989867e
--- /dev/null
+++ b/src/displayapp/Controllers.h
@@ -0,0 +1,51 @@
+#pragma once
+namespace Pinetime {
+  namespace Applications {
+    class DisplayApp;
+  }
+  namespace Components {
+    class LittleVgl;
+  }
+  namespace Controllers {
+    class Battery;
+    class Ble;
+    class DateTime;
+    class NotificationManager;
+    class HeartRateController;
+    class Settings;
+    class MotorController;
+    class MotionController;
+    class AlarmController;
+    class BrightnessController;
+    class WeatherService;
+    class FS;
+    class Timer;
+    class MusicService;
+    class NavigationService;
+  }
+  namespace System {
+    class SystemTask;
+  }
+  namespace Applications {
+    struct AppControllers {
+      const Pinetime::Controllers::Battery& batteryController;
+      const Pinetime::Controllers::Ble& bleController;
+      Pinetime::Controllers::DateTime& dateTimeController;
+      Pinetime::Controllers::NotificationManager& notificationManager;
+      Pinetime::Controllers::HeartRateController& heartRateController;
+      Pinetime::Controllers::Settings& settingsController;
+      Pinetime::Controllers::MotorController& motorController;
+      Pinetime::Controllers::MotionController& motionController;
+      Pinetime::Controllers::AlarmController& alarmController;
+      Pinetime::Controllers::BrightnessController& brightnessController;
+      Pinetime::Controllers::WeatherService* weatherController;
+      Pinetime::Controllers::FS& filesystem;
+      Pinetime::Controllers::Timer& timer;
+      Pinetime::System::SystemTask* systemTask;
+      Pinetime::Applications::DisplayApp* displayApp;
+      Pinetime::Components::LittleVgl& lvgl;
+      Pinetime::Controllers::MusicService* musicService;
+      Pinetime::Controllers::NavigationService* navigationService;
+    };
+  }
+}
\ No newline at end of file
diff --git a/src/displayapp/DisplayApp.cpp b/src/displayapp/DisplayApp.cpp
index 682ea12cb3..a195361ddb 100644
--- a/src/displayapp/DisplayApp.cpp
+++ b/src/displayapp/DisplayApp.cpp
@@ -50,6 +50,7 @@
 #include "displayapp/screens/settings/SettingBluetooth.h"
 
 #include "libs/lv_conf.h"
+#include "UserApps.h"
 
 using namespace Pinetime::Applications;
 using namespace Pinetime::Applications::Display;
@@ -96,7 +97,12 @@ DisplayApp::DisplayApp(Drivers::St7789& lcd,
     touchHandler {touchHandler},
     filesystem {filesystem},
     lvgl {lcd, filesystem},
-    timer(this, TimerCallback) {
+    timer(this, TimerCallback),
+    controllers{
+      batteryController, bleController, dateTimeController, notificationManager, heartRateController,
+      settingsController, motorController, motionController, alarmController, brightnessController,
+      nullptr, filesystem, timer, nullptr, this, lvgl, nullptr, nullptr}
+  {
 }
 
 void DisplayApp::Start(System::BootErrors error) {
@@ -402,14 +408,21 @@ void DisplayApp::LoadScreen(Apps app, DisplayApp::FullRefreshDirections directio
   SetFullRefresh(direction);
 
   switch (app) {
-    case Apps::Launcher:
-      currentScreen =
-        std::make_unique<Screens::ApplicationList>(this, settingsController, batteryController, bleController, dateTimeController, filesystem);
-      break;
-    case Apps::Motion:
-      // currentScreen = std::make_unique<Screens::Motion>(motionController);
-      // break;
-    case Apps::None:
+    case Apps::Launcher: {
+      std::array<Screens::Tile::Applications, UserAppTypes::Count> apps;
+      int i = 0;
+      for (const auto& userApp : userApps) {
+        apps[i++] = Screens::Tile::Applications {userApp.icon, userApp.app, true};
+      }
+      currentScreen = std::make_unique<Screens::ApplicationList>(this,
+                                                                 settingsController,
+                                                                 batteryController,
+                                                                 bleController,
+                                                                 dateTimeController,
+                                                                 filesystem,
+                                                                 std::move(apps));
+    }
+    break;
     case Apps::Clock:
       currentScreen = std::make_unique<Screens::Clock>(dateTimeController,
                                                        batteryController,
@@ -421,7 +434,6 @@ void DisplayApp::LoadScreen(Apps app, DisplayApp::FullRefreshDirections directio
                                                        systemTask->nimble().weather(),
                                                        filesystem);
       break;
-
     case Apps::Error:
       currentScreen = std::make_unique<Screens::Error>(bootError);
       break;
@@ -453,14 +465,6 @@ void DisplayApp::LoadScreen(Apps app, DisplayApp::FullRefreshDirections directio
                                                                *systemTask,
                                                                Screens::Notifications::Modes::Preview);
       break;
-    case Apps::Timer:
-      currentScreen = std::make_unique<Screens::Timer>(timer);
-      break;
-    case Apps::Alarm:
-      currentScreen = std::make_unique<Screens::Alarm>(alarmController, settingsController.GetClockType(), *systemTask, motorController);
-      break;
-
-    // Settings
     case Apps::QuickSettings:
       currentScreen = std::make_unique<Screens::QuickSettings>(this,
                                                                batteryController,
@@ -516,38 +520,25 @@ void DisplayApp::LoadScreen(Apps app, DisplayApp::FullRefreshDirections directio
     case Apps::FlashLight:
       currentScreen = std::make_unique<Screens::FlashLight>(*systemTask, brightnessController);
       break;
-    case Apps::StopWatch:
-      currentScreen = std::make_unique<Screens::StopWatch>(*systemTask);
-      break;
-    case Apps::Twos:
-      currentScreen = std::make_unique<Screens::Twos>();
-      break;
-    case Apps::Paint:
-      currentScreen = std::make_unique<Screens::InfiniPaint>(lvgl, motorController);
-      break;
-    case Apps::Paddle:
-      currentScreen = std::make_unique<Screens::Paddle>(lvgl);
-      break;
-    case Apps::Music:
-      currentScreen = std::make_unique<Screens::Music>(systemTask->nimble().music());
-      break;
-    case Apps::Navigation:
-      currentScreen = std::make_unique<Screens::Navigation>(systemTask->nimble().navigation());
-      break;
-    case Apps::HeartRate:
-      currentScreen = std::make_unique<Screens::HeartRate>(heartRateController, *systemTask);
-      break;
-    case Apps::Metronome:
-      currentScreen = std::make_unique<Screens::Metronome>(motorController, *systemTask);
-      break;
-    /* Weather debug app
-    case Apps::Weather:
-      currentScreen = std::make_unique<Screens::Weather>(this, systemTask->nimble().weather());
-      break;
-    */
-    case Apps::Steps:
-      currentScreen = std::make_unique<Screens::Steps>(motionController, settingsController);
+    default: {
+      const auto* d = std::find_if(userApps.begin(), userApps.end(), [app](const AppDescription& appDescription) {
+        return appDescription.app == app;
+      });
+      if (d != userApps.end())
+        currentScreen.reset(d->create(controllers));
+      else {
+        currentScreen = std::make_unique<Screens::Clock>(dateTimeController,
+                                                         batteryController,
+                                                         bleController,
+                                                         notificationManager,
+                                                         settingsController,
+                                                         heartRateController,
+                                                         motionController,
+                                                         systemTask->nimble().weather(),
+                                                         filesystem);
+      }
       break;
+    }
   }
   currentApp = app;
 }
@@ -605,6 +596,19 @@ void DisplayApp::PushMessageToSystemTask(Pinetime::System::Messages message) {
 
 void DisplayApp::Register(Pinetime::System::SystemTask* systemTask) {
   this->systemTask = systemTask;
+  this->controllers.systemTask = systemTask;
+}
+
+void DisplayApp::Register(Pinetime::Controllers::WeatherService* weatherService) {
+  this->controllers.weatherController = weatherService;
+}
+
+void DisplayApp::Register(Pinetime::Controllers::MusicService* musicService) {
+  this->controllers.musicService = musicService;
+}
+
+void DisplayApp::Register(Pinetime::Controllers::NavigationService* NavigationService) {
+  this->controllers.navigationService = NavigationService;
 }
 
 void DisplayApp::ApplyBrightness() {
diff --git a/src/displayapp/DisplayApp.h b/src/displayapp/DisplayApp.h
index f537651dbf..7dbac850aa 100644
--- a/src/displayapp/DisplayApp.h
+++ b/src/displayapp/DisplayApp.h
@@ -20,6 +20,7 @@
 #include "BootErrors.h"
 
 #include "utility/StaticStack.h"
+#include "displayapp/Controllers.h"
 
 namespace Pinetime {
 
@@ -73,6 +74,9 @@ namespace Pinetime {
       void SetFullRefresh(FullRefreshDirections direction);
 
       void Register(Pinetime::System::SystemTask* systemTask);
+      void Register(Pinetime::Controllers::WeatherService* weatherService);
+      void Register(Pinetime::Controllers::MusicService* musicService);
+      void Register(Pinetime::Controllers::NavigationService* NavigationService);
 
     private:
       Pinetime::Drivers::St7789& lcd;
@@ -96,6 +100,7 @@ namespace Pinetime {
       Pinetime::Components::LittleVgl lvgl;
       Pinetime::Controllers::Timer timer;
 
+      AppControllers controllers;
       TaskHandle_t taskHandle;
 
       States state = States::Running;
diff --git a/src/displayapp/UserApps.h b/src/displayapp/UserApps.h
new file mode 100644
index 0000000000..d0165cf9de
--- /dev/null
+++ b/src/displayapp/UserApps.h
@@ -0,0 +1,36 @@
+#pragma once
+#include "Apps.h"
+#include "Controllers.h"
+
+#include "displayapp/screens/Alarm.h"
+#include "displayapp/screens/Timer.h"
+#include "displayapp/screens/Twos.h"
+#include "displayapp/screens/Tile.h"
+#include "displayapp/screens/ApplicationList.h"
+#include "displayapp/screens/Clock.h"
+
+namespace Pinetime {
+  namespace Applications {
+    namespace Screens {
+      class Screen;
+    }
+
+    struct AppDescription {
+      Apps app;
+      const char* icon;
+      Screens::Screen* (*create)(AppControllers& controllers);
+    };
+
+    template <Apps t>
+    consteval AppDescription CreateAppDescription() {
+      return {AppTraits<t>::app, AppTraits<t>::icon, &AppTraits<t>::Create};
+    }
+
+    template <template<Apps...> typename T, Apps ...ts>
+    consteval std::array<AppDescription, sizeof...(ts)> CreateAppDescriptions(T<ts...>) {
+      return {CreateAppDescription<ts>()...};
+    }
+
+    constexpr auto userApps = CreateAppDescriptions(UserAppTypes {});
+  }
+}
diff --git a/src/displayapp/screens/Alarm.cpp b/src/displayapp/screens/Alarm.cpp
index 4e6ce79747..cbc702f312 100644
--- a/src/displayapp/screens/Alarm.cpp
+++ b/src/displayapp/screens/Alarm.cpp
@@ -19,6 +19,10 @@
 #include "displayapp/screens/Screen.h"
 #include "displayapp/screens/Symbols.h"
 #include "displayapp/InfiniTimeTheme.h"
+#include "components/settings/Settings.h"
+#include "components/alarm/AlarmController.h"
+#include "components/motor/MotorController.h"
+#include "systemtask/SystemTask.h"
 
 using namespace Pinetime::Applications::Screens;
 using Pinetime::Controllers::AlarmController;
diff --git a/src/displayapp/screens/Alarm.h b/src/displayapp/screens/Alarm.h
index 911773662a..efa38eb74f 100644
--- a/src/displayapp/screens/Alarm.h
+++ b/src/displayapp/screens/Alarm.h
@@ -17,21 +17,22 @@
 */
 #pragma once
 
+#include "displayapp/Apps.h"
+#include "components/settings/Settings.h"
 #include "displayapp/screens/Screen.h"
-#include "systemtask/SystemTask.h"
-#include "displayapp/LittleVgl.h"
-#include "components/alarm/AlarmController.h"
 #include "displayapp/widgets/Counter.h"
+#include "displayapp/Controllers.h"
+#include "Symbols.h"
 
 namespace Pinetime {
   namespace Applications {
     namespace Screens {
       class Alarm : public Screen {
       public:
-        Alarm(Controllers::AlarmController& alarmController,
-              Controllers::Settings::ClockType clockType,
-              System::SystemTask& systemTask,
-              Controllers::MotorController& motorController);
+        explicit Alarm(Controllers::AlarmController& alarmController,
+                       Controllers::Settings::ClockType clockType,
+                       System::SystemTask& systemTask,
+                       Controllers::MotorController& motorController);
         ~Alarm() override;
         void SetAlerting();
         void OnButtonEvent(lv_obj_t* obj, lv_event_t event);
@@ -63,6 +64,15 @@ namespace Pinetime {
         Widgets::Counter hourCounter = Widgets::Counter(0, 23, jetbrains_mono_76);
         Widgets::Counter minuteCounter = Widgets::Counter(0, 59, jetbrains_mono_76);
       };
+    }
+    template<>
+    struct AppTraits<Apps::Alarm> {
+      static constexpr Apps app = Apps::Alarm;
+      static constexpr const char* icon = Screens::Symbols::clock;
+      static Screens::Screen *Create(AppControllers& controllers) { return new Screens::Alarm(controllers.alarmController,
+                                  controllers.settingsController.GetClockType(),
+                                  *controllers.systemTask,
+                                  controllers.motorController); };
     };
-  };
+  }
 }
diff --git a/src/displayapp/screens/ApplicationList.cpp b/src/displayapp/screens/ApplicationList.cpp
index 6014cf53e0..e5e26098d8 100644
--- a/src/displayapp/screens/ApplicationList.cpp
+++ b/src/displayapp/screens/ApplicationList.cpp
@@ -1,8 +1,9 @@
 #include "displayapp/screens/ApplicationList.h"
+#include "displayapp/screens/Tile.h"
 #include <lvgl/lvgl.h>
 #include <functional>
-#include "displayapp/Apps.h"
-#include "displayapp/DisplayApp.h"
+#include  <algorithm>
+#include "components/settings/Settings.h"
 
 using namespace Pinetime::Applications::Screens;
 
@@ -16,18 +17,20 @@ auto ApplicationList::CreateScreenList() const {
   return screens;
 }
 
-ApplicationList::ApplicationList(Pinetime::Applications::DisplayApp* app,
+ApplicationList::ApplicationList(DisplayApp* app,
                                  Pinetime::Controllers::Settings& settingsController,
                                  const Pinetime::Controllers::Battery& batteryController,
                                  const Pinetime::Controllers::Ble& bleController,
                                  Controllers::DateTime& dateTimeController,
-                                 Pinetime::Controllers::FS& filesystem)
+                                 Pinetime::Controllers::FS& filesystem,
+                                 std::array<Tile::Applications, UserAppTypes::Count>&& apps)
   : app {app},
     settingsController {settingsController},
     batteryController {batteryController},
     bleController {bleController},
     dateTimeController {dateTimeController},
     filesystem{filesystem},
+    apps{std::move(apps)},
     screens {app, settingsController.GetAppMenu(), CreateScreenList(), Screens::ScreenListModes::UpDown} {
 }
 
@@ -40,9 +43,14 @@ bool ApplicationList::OnTouchEvent(Pinetime::Applications::TouchEvents event) {
 }
 
 std::unique_ptr<Screen> ApplicationList::CreateScreen(unsigned int screenNum) const {
-  std::array<Tile::Applications, appsPerScreen> apps;
-  for (int i = 0; i < appsPerScreen; i++) {
-    apps[i] = applications[screenNum * appsPerScreen + i];
+  std::array<Tile::Applications, appsPerScreen> pageApps;
+
+  for(int i = 0; i < appsPerScreen; i++) {
+    if(i+(screenNum * appsPerScreen) >= apps.size()) {
+      pageApps[i] = {"", Pinetime::Applications::Apps::None, false};
+    } else {
+      pageApps[i] = apps[i + (screenNum * appsPerScreen)];
+    }
   }
 
   return std::make_unique<Screens::Tile>(screenNum,
@@ -52,5 +60,5 @@ std::unique_ptr<Screen> ApplicationList::CreateScreen(unsigned int screenNum) co
                                          batteryController,
                                          bleController,
                                          dateTimeController,
-                                         apps);
+                                         pageApps);
 }
diff --git a/src/displayapp/screens/ApplicationList.h b/src/displayapp/screens/ApplicationList.h
index 371ee710b5..2ad9c7c717 100644
--- a/src/displayapp/screens/ApplicationList.h
+++ b/src/displayapp/screens/ApplicationList.h
@@ -2,15 +2,12 @@
 
 #include <array>
 #include <memory>
-
-#include "displayapp/screens/Screen.h"
-#include "displayapp/screens/ScreenList.h"
-#include "components/datetime/DateTimeController.h"
-#include "components/settings/Settings.h"
-#include "components/battery/BatteryController.h"
-#include "displayapp/screens/Symbols.h"
-#include "displayapp/screens/Tile.h"
-#include "displayapp/screens/Navigation.h"
+#include "displayapp/Apps.h"
+#include "Screen.h"
+#include "ScreenList.h"
+#include "displayapp/Controllers.h"
+#include "Symbols.h"
+#include "Tile.h"
 
 namespace Pinetime {
   namespace Applications {
@@ -22,7 +19,8 @@ namespace Pinetime {
                                  const Pinetime::Controllers::Battery& batteryController,
                                  const Pinetime::Controllers::Ble& bleController,
                                  Controllers::DateTime& dateTimeController,
-                                 Pinetime::Controllers::FS& filesystem);
+                                 Pinetime::Controllers::FS& filesystem,
+                                 std::array<Tile::Applications, UserAppTypes::Count>&& apps);
         ~ApplicationList() override;
         bool OnTouchEvent(TouchEvents event) override;
 
@@ -36,29 +34,13 @@ namespace Pinetime {
         const Pinetime::Controllers::Ble& bleController;
         Controllers::DateTime& dateTimeController;
         Pinetime::Controllers::FS& filesystem;
+        std::array<Tile::Applications, UserAppTypes::Count> apps;
 
         static constexpr int appsPerScreen = 6;
 
         // Increment this when more space is needed
-        static constexpr int nScreens = 2;
-
-        std::array<Tile::Applications, appsPerScreen * nScreens> applications {{
-          {Symbols::stopWatch, Apps::StopWatch, true},
-          {Symbols::clock, Apps::Alarm, true},
-          {Symbols::hourGlass, Apps::Timer, true},
-          {Symbols::shoe, Apps::Steps, true},
-          {Symbols::heartBeat, Apps::HeartRate, true},
-          {Symbols::music, Apps::Music, true},
-
-          {Symbols::paintbrush, Apps::Paint, true},
-          {Symbols::paddle, Apps::Paddle, true},
-          {"2", Apps::Twos, true},
-          {Symbols::drum, Apps::Metronome, true},
-          {Symbols::map, Apps::Navigation, Applications::Screens::Navigation::IsAvailable(filesystem)},
-          {Symbols::none, Apps::None, false},
+        static constexpr int nScreens = (UserAppTypes::Count/appsPerScreen)+1;
 
-          // {"M", Apps::Motion},
-        }};
         ScreenList<nScreens> screens;
       };
     }
diff --git a/src/displayapp/screens/Clock.h b/src/displayapp/screens/Clock.h
index f3591f43c6..e67c0260f4 100644
--- a/src/displayapp/screens/Clock.h
+++ b/src/displayapp/screens/Clock.h
@@ -1,13 +1,12 @@
 #pragma once
 
-#include <lvgl/src/lv_core/lv_obj.h>
 #include <chrono>
 #include <cstdint>
 #include <memory>
-#include <components/heartrate/HeartRateController.h>
+#include "displayapp/Controllers.h"
 #include "displayapp/screens/Screen.h"
-#include "components/datetime/DateTimeController.h"
-#include "components/ble/weather/WeatherService.h"
+#include "displayapp/Apps.h"
+#include "Symbols.h"
 
 namespace Pinetime {
   namespace Controllers {
@@ -16,6 +15,10 @@ namespace Pinetime {
     class Ble;
     class NotificationManager;
     class MotionController;
+    class DateTime;
+    class HeartRateController;
+    class WeatherService;
+    class FS;
   }
 
   namespace Applications {
diff --git a/src/displayapp/screens/HeartRate.h b/src/displayapp/screens/HeartRate.h
index 78ae63db5f..85da8dee31 100644
--- a/src/displayapp/screens/HeartRate.h
+++ b/src/displayapp/screens/HeartRate.h
@@ -4,6 +4,7 @@
 #include <chrono>
 #include "displayapp/screens/Screen.h"
 #include "systemtask/SystemTask.h"
+#include "Symbols.h"
 #include <lvgl/src/lv_core/lv_style.h>
 #include <lvgl/src/lv_core/lv_obj.h>
 
@@ -37,5 +38,13 @@ namespace Pinetime {
         lv_task_t* taskRefresh;
       };
     }
+    template <>
+    struct AppTraits<Apps::HeartRate> {
+      static constexpr Apps app = Apps::HeartRate;
+      static constexpr const char* icon = Screens::Symbols::heartBeat;
+      static Screens::Screen* Create(AppControllers& controllers) {
+        return new Screens::HeartRate(controllers.heartRateController, *controllers.systemTask);
+      };
+    };
   }
 }
diff --git a/src/displayapp/screens/InfiniPaint.h b/src/displayapp/screens/InfiniPaint.h
index ec184c44c5..a25ace55a2 100644
--- a/src/displayapp/screens/InfiniPaint.h
+++ b/src/displayapp/screens/InfiniPaint.h
@@ -5,6 +5,9 @@
 #include <algorithm> // std::fill
 #include "displayapp/screens/Screen.h"
 #include "components/motor/MotorController.h"
+#include "Symbols.h"
+#include <displayapp/Apps.h>
+#include <displayapp/Controllers.h>
 
 namespace Pinetime {
   namespace Components {
@@ -35,5 +38,13 @@ namespace Pinetime {
         uint8_t color = 2;
       };
     }
+    template <>
+    struct AppTraits<Apps::Paint> {
+      static constexpr Apps app = Apps::Paint;
+      static constexpr const char* icon = Screens::Symbols::paintbrush;
+      static Screens::Screen* Create(AppControllers& controllers) {
+        return new Screens::InfiniPaint(controllers.lvgl, controllers.motorController);
+      };
+    };
   }
 }
diff --git a/src/displayapp/screens/Metronome.h b/src/displayapp/screens/Metronome.h
index 13b0d66491..8820962dca 100644
--- a/src/displayapp/screens/Metronome.h
+++ b/src/displayapp/screens/Metronome.h
@@ -3,6 +3,7 @@
 #include "systemtask/SystemTask.h"
 #include "components/motor/MotorController.h"
 #include "displayapp/screens/Screen.h"
+#include "Symbols.h"
 
 namespace Pinetime {
   namespace Applications {
@@ -36,5 +37,13 @@ namespace Pinetime {
         lv_task_t* taskRefresh;
       };
     }
+    template <>
+    struct AppTraits<Apps::Metronome> {
+      static constexpr Apps app = Apps::Metronome;
+      static constexpr const char* icon = Screens::Symbols::drum;
+      static Screens::Screen* Create(AppControllers& controllers) {
+        return new Screens::Metronome(controllers.motorController, *controllers.systemTask);
+      };
+    };
   }
 }
diff --git a/src/displayapp/screens/Motion.h b/src/displayapp/screens/Motion.h
index e4cbe48393..3ef570d675 100644
--- a/src/displayapp/screens/Motion.h
+++ b/src/displayapp/screens/Motion.h
@@ -6,6 +6,8 @@
 #include <lvgl/src/lv_core/lv_style.h>
 #include <lvgl/src/lv_core/lv_obj.h>
 #include <components/motion/MotionController.h>
+#include "displayapp/Controllers.h"
+#include "displayapp/Apps.h"
 
 namespace Pinetime {
   namespace Applications {
@@ -30,5 +32,13 @@ namespace Pinetime {
         lv_task_t* taskRefresh;
       };
     }
+    template <>
+    struct AppTraits<Apps::Motion> {
+      static constexpr Apps app = Apps::Motion;
+      static constexpr const char* icon = "M";
+      static Screens::Screen* Create(AppControllers& controllers) {
+        return new Screens::Motion(controllers.motionController);
+      };
+    };
   }
 }
diff --git a/src/displayapp/screens/Music.h b/src/displayapp/screens/Music.h
index 847c6e7444..acbb63120d 100644
--- a/src/displayapp/screens/Music.h
+++ b/src/displayapp/screens/Music.h
@@ -21,6 +21,9 @@
 #include <lvgl/src/lv_core/lv_obj.h>
 #include <string>
 #include "displayapp/screens/Screen.h"
+#include "displayapp/Apps.h"
+#include "displayapp/Controllers.h"
+#include "Symbols.h"
 
 namespace Pinetime {
   namespace Controllers {
@@ -82,5 +85,13 @@ namespace Pinetime {
         /** Watchapp */
       };
     }
+    template <>
+    struct AppTraits<Apps::Music> {
+      static constexpr Apps app = Apps::Music;
+      static constexpr const char* icon = Screens::Symbols::music;
+      static Screens::Screen* Create(AppControllers& controllers) {
+        return new Screens::Music(*controllers.musicService);
+      };
+    };
   }
 }
diff --git a/src/displayapp/screens/Navigation.h b/src/displayapp/screens/Navigation.h
index eb243b011a..d54df13ce3 100644
--- a/src/displayapp/screens/Navigation.h
+++ b/src/displayapp/screens/Navigation.h
@@ -22,6 +22,9 @@
 #include <string>
 #include "displayapp/screens/Screen.h"
 #include <array>
+#include "displayapp/Apps.h"
+#include "displayapp/Controllers.h"
+#include "Symbols.h"
 
 namespace Pinetime {
   namespace Controllers {
@@ -55,5 +58,13 @@ namespace Pinetime {
         lv_task_t* taskRefresh;
       };
     }
+    template <>
+    struct AppTraits<Apps::Navigation> {
+      static constexpr Apps app = Apps::Navigation;
+      static constexpr const char* icon = Screens::Symbols::map;
+      static Screens::Screen* Create(AppControllers& controllers) {
+        return new Screens::Navigation(*controllers.navigationService);
+      };
+    };
   }
 }
diff --git a/src/displayapp/screens/Paddle.h b/src/displayapp/screens/Paddle.h
index 33dac191b5..0670e5b1f1 100644
--- a/src/displayapp/screens/Paddle.h
+++ b/src/displayapp/screens/Paddle.h
@@ -3,6 +3,9 @@
 #include <lvgl/lvgl.h>
 #include <cstdint>
 #include "displayapp/screens/Screen.h"
+#include "displayapp/Apps.h"
+#include "displayapp/Controllers.h"
+#include "Symbols.h"
 
 namespace Pinetime {
   namespace Components {
@@ -45,5 +48,13 @@ namespace Pinetime {
         lv_task_t* taskRefresh;
       };
     }
+    template <>
+    struct AppTraits<Apps::Paddle> {
+      static constexpr Apps app = Apps::Paddle;
+      static constexpr const char* icon = Screens::Symbols::paddle;
+      static Screens::Screen* Create(AppControllers& controllers) {
+        return new Screens::Paddle(controllers.lvgl);
+      };
+    };
   }
 }
diff --git a/src/displayapp/screens/Steps.h b/src/displayapp/screens/Steps.h
index 5dc07eff94..5299d67f9f 100644
--- a/src/displayapp/screens/Steps.h
+++ b/src/displayapp/screens/Steps.h
@@ -4,6 +4,9 @@
 #include <lvgl/lvgl.h>
 #include "displayapp/screens/Screen.h"
 #include <components/motion/MotionController.h>
+#include "displayapp/Apps.h"
+#include "displayapp/Controllers.h"
+#include "Symbols.h"
 
 namespace Pinetime {
 
@@ -39,5 +42,13 @@ namespace Pinetime {
         lv_task_t* taskRefresh;
       };
     }
+    template <>
+    struct AppTraits<Apps::Steps> {
+      static constexpr Apps app = Apps::Steps;
+      static constexpr const char* icon = Screens::Symbols::shoe;
+      static Screens::Screen* Create(AppControllers& controllers) {
+        return new Screens::Steps(controllers.motionController, controllers.settingsController);
+      };
+    };
   }
 }
diff --git a/src/displayapp/screens/StopWatch.h b/src/displayapp/screens/StopWatch.h
index d1acd1624e..c3550fc41d 100644
--- a/src/displayapp/screens/StopWatch.h
+++ b/src/displayapp/screens/StopWatch.h
@@ -7,50 +7,65 @@
 #include "portmacro_cmsis.h"
 
 #include "systemtask/SystemTask.h"
+#include "displayapp/Apps.h"
+#include "displayapp/Controllers.h"
+#include "Symbols.h"
 
-namespace Pinetime::Applications::Screens {
-
-  enum class States { Init, Running, Halted };
-
-  struct TimeSeparated_t {
-    int hours;
-    int mins;
-    int secs;
-    int hundredths;
-  };
-
-  class StopWatch : public Screen {
-  public:
-    explicit StopWatch(System::SystemTask& systemTask);
-    ~StopWatch() override;
-    void Refresh() override;
-
-    void playPauseBtnEventHandler();
-    void stopLapBtnEventHandler();
-    bool OnButtonPushed() override;
-
-  private:
-    void SetInterfacePaused();
-    void SetInterfaceRunning();
-    void SetInterfaceStopped();
-
-    void Reset();
-    void Start();
-    void Pause();
-
-    Pinetime::System::SystemTask& systemTask;
-    States currentState = States::Init;
-    TickType_t startTime;
-    TickType_t oldTimeElapsed = 0;
-    TickType_t blinkTime = 0;
-    static constexpr int maxLapCount = 20;
-    TickType_t laps[maxLapCount + 1];
-    static constexpr int displayedLaps = 2;
-    int lapsDone = 0;
-    lv_obj_t *time, *msecTime, *btnPlayPause, *btnStopLap, *txtPlayPause, *txtStopLap;
-    lv_obj_t* lapText;
-    bool isHoursLabelUpdated = false;
-
-    lv_task_t* taskRefresh;
-  };
+namespace Pinetime {
+  namespace Applications {
+    namespace Screens {
+
+      enum class States { Init, Running, Halted };
+
+      struct TimeSeparated_t {
+        int hours;
+        int mins;
+        int secs;
+        int hundredths;
+      };
+
+      class StopWatch : public Screen {
+      public:
+        explicit StopWatch(System::SystemTask& systemTask);
+        ~StopWatch() override;
+        void Refresh() override;
+
+        void playPauseBtnEventHandler();
+        void stopLapBtnEventHandler();
+        bool OnButtonPushed() override;
+
+      private:
+        void SetInterfacePaused();
+        void SetInterfaceRunning();
+        void SetInterfaceStopped();
+
+        void Reset();
+        void Start();
+        void Pause();
+
+        Pinetime::System::SystemTask& systemTask;
+        States currentState = States::Init;
+        TickType_t startTime;
+        TickType_t oldTimeElapsed = 0;
+        TickType_t blinkTime = 0;
+        static constexpr int maxLapCount = 20;
+        TickType_t laps[maxLapCount + 1];
+        static constexpr int displayedLaps = 2;
+        int lapsDone = 0;
+        lv_obj_t *time, *msecTime, *btnPlayPause, *btnStopLap, *txtPlayPause, *txtStopLap;
+        lv_obj_t* lapText;
+        bool isHoursLabelUpdated = false;
+
+        lv_task_t* taskRefresh;
+      };
+    }
+    template <>
+    struct AppTraits<Apps::StopWatch> {
+      static constexpr Apps app = Apps::StopWatch;
+      static constexpr const char* icon = Screens::Symbols::stopWatch;
+      static Screens::Screen* Create(AppControllers& controllers) {
+        return new Screens::StopWatch(*controllers.systemTask);
+      };
+    };
+  }
 }
diff --git a/src/displayapp/screens/Tile.cpp b/src/displayapp/screens/Tile.cpp
index 343755e3f0..7c392c59e5 100644
--- a/src/displayapp/screens/Tile.cpp
+++ b/src/displayapp/screens/Tile.cpp
@@ -1,5 +1,4 @@
 #include "displayapp/screens/Tile.h"
-#include "displayapp/DisplayApp.h"
 #include "displayapp/screens/BatteryIcon.h"
 #include "components/ble/BleController.h"
 #include "displayapp/InfiniTimeTheme.h"
diff --git a/src/displayapp/screens/Timer.cpp b/src/displayapp/screens/Timer.cpp
index d94887404e..a1ede6bed6 100644
--- a/src/displayapp/screens/Timer.cpp
+++ b/src/displayapp/screens/Timer.cpp
@@ -62,7 +62,7 @@ Timer::Timer(Controllers::Timer& timerController) : timer {timerController} {
   txtPlayPause = lv_label_create(lv_scr_act(), nullptr);
   lv_obj_align(txtPlayPause, btnPlayPause, LV_ALIGN_CENTER, 0, 0);
 
-  if (timerController.IsRunning()) {
+  if (timer.IsRunning()) {
     SetTimerRunning();
   } else {
     SetTimerStopped();
diff --git a/src/displayapp/screens/Timer.h b/src/displayapp/screens/Timer.h
index e452a9d9dc..f8e337c2ec 100644
--- a/src/displayapp/screens/Timer.h
+++ b/src/displayapp/screens/Timer.h
@@ -8,38 +8,48 @@
 #include <lvgl/lvgl.h>
 
 #include "components/timer/Timer.h"
-
-namespace Pinetime::Applications::Screens {
-  class Timer : public Screen {
-  public:
-    Timer(Controllers::Timer& timerController);
-    ~Timer() override;
-    void Refresh() override;
-    void Reset();
-    void ToggleRunning();
-    void ButtonPressed();
-    void MaskReset();
-
-  private:
-    void SetTimerRunning();
-    void SetTimerStopped();
-    void UpdateMask();
-    Controllers::Timer& timer;
-
-    lv_obj_t* btnPlayPause;
-    lv_obj_t* txtPlayPause;
-
-    lv_obj_t* btnObjectMask;
-    lv_obj_t* highlightObjectMask;
-    lv_objmask_mask_t* btnMask;
-    lv_objmask_mask_t* highlightMask;
-
-    lv_task_t* taskRefresh;
-    Widgets::Counter minuteCounter = Widgets::Counter(0, 59, jetbrains_mono_76);
-    Widgets::Counter secondCounter = Widgets::Counter(0, 59, jetbrains_mono_76);
-
-    bool buttonPressing = false;
-    lv_coord_t maskPosition = 0;
-    TickType_t pressTime = 0;
+#include "Symbols.h"
+
+namespace Pinetime::Applications{
+  namespace Screens {
+    class Timer : public Screen {
+    public:
+      Timer(Controllers::Timer& timerController);
+      ~Timer() override;
+      void Refresh() override;
+      void Reset();
+      void ToggleRunning();
+      void ButtonPressed();
+      void MaskReset();
+
+    private:
+      void SetTimerRunning();
+      void SetTimerStopped();
+      void UpdateMask();
+      Pinetime::Controllers::Timer& timer;
+
+      lv_obj_t* btnPlayPause;
+      lv_obj_t* txtPlayPause;
+
+      lv_obj_t* btnObjectMask;
+      lv_obj_t* highlightObjectMask;
+      lv_objmask_mask_t* btnMask;
+      lv_objmask_mask_t* highlightMask;
+
+      lv_task_t* taskRefresh;
+      Widgets::Counter minuteCounter = Widgets::Counter(0, 59, jetbrains_mono_76);
+      Widgets::Counter secondCounter = Widgets::Counter(0, 59, jetbrains_mono_76);
+
+      bool buttonPressing = false;
+      lv_coord_t maskPosition = 0;
+      TickType_t pressTime = 0;
+    };
+  }
+
+  template<>
+  struct AppTraits<Apps::Timer> {
+    static constexpr Apps app = Apps::Timer;
+    static constexpr const char* icon = Screens::Symbols::hourGlass;
+    static Screens::Screen *Create(AppControllers& controllers) { return new Screens::Timer(controllers.timer); };
   };
 }
diff --git a/src/displayapp/screens/Twos.h b/src/displayapp/screens/Twos.h
index e731eae62f..4e6980f53a 100644
--- a/src/displayapp/screens/Twos.h
+++ b/src/displayapp/screens/Twos.h
@@ -1,7 +1,8 @@
 #pragma once
 
-#include <lvgl/src/lv_core/lv_obj.h>
+#include "displayapp/Apps.h"
 #include "displayapp/screens/Screen.h"
+#include "displayapp/Controllers.h"
 
 namespace Pinetime {
   namespace Applications {
@@ -35,5 +36,11 @@ namespace Pinetime {
         bool placeNewTile();
       };
     }
+    template<>
+    struct AppTraits<Apps::Twos> {
+      static constexpr Apps app = Apps::Twos;
+      static constexpr const char* icon = "2";
+      static Screens::Screen *Create(AppControllers& /*controllers*/) { return new Screens::Twos(); };
+    };
   }
 }
diff --git a/src/displayapp/screens/Weather.h b/src/displayapp/screens/Weather.h
index 459534aa2a..888dc257cf 100644
--- a/src/displayapp/screens/Weather.h
+++ b/src/displayapp/screens/Weather.h
@@ -1,9 +1,12 @@
 #pragma once
 
 #include <memory>
-#include <components/ble/weather/WeatherService.h>
+#include "components/ble/weather/WeatherService.h"
 #include "Screen.h"
 #include "ScreenList.h"
+#include "displayapp/Apps.h"
+#include "displayapp/Controllers.h"
+#include "Symbols.h"
 
 namespace Pinetime {
   namespace Applications {
@@ -41,5 +44,13 @@ namespace Pinetime {
         std::unique_ptr<Screen> CreateScreenHumidity();
       };
     }
+    template <>
+    struct AppTraits<Apps::Weather> {
+      static constexpr Apps app = Apps::Weather;
+      static constexpr const char* icon = Screens::Symbols::sun;
+      static Screens::Screen* Create(AppControllers& controllers) {
+        return new Screens::Weather(controllers.displayApp, *controllers.weatherController);
+      };
+    };
   }
 }
diff --git a/src/drivers/SpiMaster.cpp b/src/drivers/SpiMaster.cpp
index 1a2fab9c27..3446d639fa 100644
--- a/src/drivers/SpiMaster.cpp
+++ b/src/drivers/SpiMaster.cpp
@@ -131,8 +131,8 @@ void SpiMaster::OnEndEvent() {
   if (s > 0) {
     auto currentSize = std::min((size_t) 255, s);
     PrepareTx(currentBufferAddr, currentSize);
-    currentBufferAddr += currentSize;
-    currentBufferSize -= currentSize;
+    currentBufferAddr = currentBufferAddr + currentSize;
+    currentBufferSize = currentBufferSize - currentSize;
 
     spiBaseAddress->TASKS_START = 1;
   } else {
@@ -153,7 +153,7 @@ void SpiMaster::OnEndEvent() {
 void SpiMaster::OnStartedEvent() {
 }
 
-void SpiMaster::PrepareTx(const volatile uint32_t bufferAddress, const volatile size_t size) {
+void SpiMaster::PrepareTx(const uint32_t bufferAddress, const size_t size) {
   spiBaseAddress->TXD.PTR = bufferAddress;
   spiBaseAddress->TXD.MAXCNT = size;
   spiBaseAddress->TXD.LIST = 0;
@@ -163,7 +163,7 @@ void SpiMaster::PrepareTx(const volatile uint32_t bufferAddress, const volatile
   spiBaseAddress->EVENTS_END = 0;
 }
 
-void SpiMaster::PrepareRx(const volatile uint32_t bufferAddress, const volatile size_t size) {
+void SpiMaster::PrepareRx(const uint32_t bufferAddress, const size_t size) {
   spiBaseAddress->TXD.PTR = 0;
   spiBaseAddress->TXD.MAXCNT = 0;
   spiBaseAddress->TXD.LIST = 0;
@@ -195,8 +195,8 @@ bool SpiMaster::Write(uint8_t pinCsn, const uint8_t* data, size_t size) {
 
   auto currentSize = std::min((size_t) 255, (size_t) currentBufferSize);
   PrepareTx(currentBufferAddr, currentSize);
-  currentBufferSize -= currentSize;
-  currentBufferAddr += currentSize;
+  currentBufferSize = currentBufferSize - currentSize;
+  currentBufferAddr = currentBufferAddr + currentSize;
   spiBaseAddress->TASKS_START = 1;
 
   if (size == 1) {
diff --git a/src/drivers/Watchdog.cpp b/src/drivers/Watchdog.cpp
index 6c2c963be3..eeeb6cfdf5 100644
--- a/src/drivers/Watchdog.cpp
+++ b/src/drivers/Watchdog.cpp
@@ -41,7 +41,7 @@ namespace {
     // RRED (Reload Register Enable) is a bitfield of 8 bits. Each bit represent
     // one of the eight reload registers available.
     // In this case, we enable only the first one.
-    NRF_WDT->RREN |= 1;
+    NRF_WDT->RREN = NRF_WDT->RREN | 1;
   }
 
   /// Returns the reset reason provided by the POWER subsystem
diff --git a/src/systemtask/SystemTask.cpp b/src/systemtask/SystemTask.cpp
index e59a0ff7a4..b245e39227 100644
--- a/src/systemtask/SystemTask.cpp
+++ b/src/systemtask/SystemTask.cpp
@@ -136,6 +136,9 @@ void SystemTask::Work() {
   settingsController.Init();
 
   displayApp.Register(this);
+  displayApp.Register(&nimbleController.weather());
+  displayApp.Register(&nimbleController.music());
+  displayApp.Register(&nimbleController.navigation());
   displayApp.Start(bootError);
 
   heartRateSensor.Init();

From 3886ebf0942f79f141ed5dd3a65bdf880f990efc Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Jean-Fran=C3=A7ois=20Milants?= <jf@codingfield.com>
Date: Mon, 23 Oct 2023 21:43:05 +0200
Subject: [PATCH 2/5] Application selection at build time

Fix DisplayAppRecovery so it builds with -std=c++20.
---
 src/components/gfx/Gfx.cpp            | 4 ++--
 src/displayapp/DisplayAppRecovery.cpp | 9 +++++++++
 src/displayapp/DisplayAppRecovery.h   | 7 +++++++
 3 files changed, 18 insertions(+), 2 deletions(-)

diff --git a/src/components/gfx/Gfx.cpp b/src/components/gfx/Gfx.cpp
index 3eaaa3fecc..d3ef3d087a 100644
--- a/src/components/gfx/Gfx.cpp
+++ b/src/components/gfx/Gfx.cpp
@@ -141,7 +141,7 @@ void Gfx::SetBackgroundColor(uint16_t color) {
 bool Gfx::GetNextBuffer(uint8_t** data, size_t& size) {
   if (!state.busy)
     return false;
-  state.remainingIterations--;
+  state.remainingIterations = state.remainingIterations-1;
   if (state.remainingIterations == 0) {
     state.busy = false;
     NotifyEndOfTransfer(state.taskToNotify);
@@ -170,7 +170,7 @@ bool Gfx::GetNextBuffer(uint8_t** data, size_t& size) {
     size = bytes_in_line * 8 * 2;
   }
 
-  state.currentIteration++;
+  state.currentIteration = state.currentIteration + 1;
 
   return true;
 }
diff --git a/src/displayapp/DisplayAppRecovery.cpp b/src/displayapp/DisplayAppRecovery.cpp
index de165c2922..9fe59c40a8 100644
--- a/src/displayapp/DisplayAppRecovery.cpp
+++ b/src/displayapp/DisplayAppRecovery.cpp
@@ -121,3 +121,12 @@ void DisplayApp::PushMessage(Display::Messages msg) {
 
 void DisplayApp::Register(Pinetime::System::SystemTask* /*systemTask*/) {
 }
+
+void DisplayApp::Register(Pinetime::Controllers::WeatherService* /*weatherService*/) {
+}
+
+void DisplayApp::Register(Pinetime::Controllers::MusicService* /*musicService*/) {
+}
+
+void DisplayApp::Register(Pinetime::Controllers::NavigationService* /*NavigationService*/) {
+}
diff --git a/src/displayapp/DisplayAppRecovery.h b/src/displayapp/DisplayAppRecovery.h
index 3ce9518773..a42d3e2fb1 100644
--- a/src/displayapp/DisplayAppRecovery.h
+++ b/src/displayapp/DisplayAppRecovery.h
@@ -34,6 +34,9 @@ namespace Pinetime {
     class AlarmController;
     class BrightnessController;
     class FS;
+    class WeatherService;
+    class MusicService;
+    class NavigationService;
   }
 
   namespace System {
@@ -66,6 +69,10 @@ namespace Pinetime {
 
       void PushMessage(Pinetime::Applications::Display::Messages msg);
       void Register(Pinetime::System::SystemTask* systemTask);
+      void Register(Pinetime::Controllers::WeatherService* weatherService);
+      void Register(Pinetime::Controllers::MusicService* musicService);
+      void Register(Pinetime::Controllers::NavigationService* NavigationService);
+
 
     private:
       TaskHandle_t taskHandle;

From 27df3ff03543985850d5c3631638d39813fcd248 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Jean-Fran=C3=A7ois=20Milants?= <jf@codingfield.com>
Date: Wed, 1 Nov 2023 20:52:47 +0100
Subject: [PATCH 3/5] Add missing new line at end of file.

---
 src/displayapp/Controllers.h | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/src/displayapp/Controllers.h b/src/displayapp/Controllers.h
index cef989867e..a2f8238880 100644
--- a/src/displayapp/Controllers.h
+++ b/src/displayapp/Controllers.h
@@ -48,4 +48,4 @@ namespace Pinetime {
       Pinetime::Controllers::NavigationService* navigationService;
     };
   }
-}
\ No newline at end of file
+}

From a868322b49c8a80dd66e9686b354a0f91c8c4a79 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Jean-Fran=C3=A7ois=20Milants?= <jf@codingfield.com>
Date: Wed, 1 Nov 2023 21:06:26 +0100
Subject: [PATCH 4/5] Fix code formatting

---
 src/components/gfx/Gfx.cpp                 |  2 +-
 src/displayapp/Apps.h                      |  3 ++-
 src/displayapp/Controllers.h               |  5 +++++
 src/displayapp/DisplayApp.cpp              | 26 ++++++++++++++++------
 src/displayapp/DisplayAppRecovery.h        |  1 -
 src/displayapp/UserApps.h                  |  2 +-
 src/displayapp/screens/Alarm.h             | 10 ++++++---
 src/displayapp/screens/ApplicationList.cpp | 10 ++++-----
 src/displayapp/screens/ApplicationList.h   |  2 +-
 src/displayapp/screens/HeartRate.h         |  2 ++
 src/displayapp/screens/InfiniPaint.h       |  2 ++
 src/displayapp/screens/Metronome.h         |  2 ++
 src/displayapp/screens/Motion.h            |  2 ++
 src/displayapp/screens/Music.h             |  2 ++
 src/displayapp/screens/Navigation.h        |  2 ++
 src/displayapp/screens/Paddle.h            |  2 ++
 src/displayapp/screens/Steps.h             |  2 ++
 src/displayapp/screens/StopWatch.h         |  2 ++
 src/displayapp/screens/Timer.h             |  9 +++++---
 src/displayapp/screens/Twos.h              |  8 +++++--
 src/displayapp/screens/Weather.h           |  2 ++
 21 files changed, 73 insertions(+), 25 deletions(-)

diff --git a/src/components/gfx/Gfx.cpp b/src/components/gfx/Gfx.cpp
index d3ef3d087a..baa6486a4a 100644
--- a/src/components/gfx/Gfx.cpp
+++ b/src/components/gfx/Gfx.cpp
@@ -141,7 +141,7 @@ void Gfx::SetBackgroundColor(uint16_t color) {
 bool Gfx::GetNextBuffer(uint8_t** data, size_t& size) {
   if (!state.busy)
     return false;
-  state.remainingIterations = state.remainingIterations-1;
+  state.remainingIterations = state.remainingIterations - 1;
   if (state.remainingIterations == 0) {
     state.busy = false;
     NotifyEndOfTransfer(state.taskToNotify);
diff --git a/src/displayapp/Apps.h b/src/displayapp/Apps.h
index d96e6ea721..0dd8157e2d 100644
--- a/src/displayapp/Apps.h
+++ b/src/displayapp/Apps.h
@@ -40,10 +40,11 @@ namespace Pinetime {
       Error,
       Weather
     };
+
     template <Apps>
     struct AppTraits {};
 
-    template<Apps ...As>
+    template <Apps... As>
     struct TypeList {
       static constexpr size_t Count = sizeof...(As);
     };
diff --git a/src/displayapp/Controllers.h b/src/displayapp/Controllers.h
index a2f8238880..df6b2284b4 100644
--- a/src/displayapp/Controllers.h
+++ b/src/displayapp/Controllers.h
@@ -1,11 +1,14 @@
 #pragma once
+
 namespace Pinetime {
   namespace Applications {
     class DisplayApp;
   }
+
   namespace Components {
     class LittleVgl;
   }
+
   namespace Controllers {
     class Battery;
     class Ble;
@@ -23,9 +26,11 @@ namespace Pinetime {
     class MusicService;
     class NavigationService;
   }
+
   namespace System {
     class SystemTask;
   }
+
   namespace Applications {
     struct AppControllers {
       const Pinetime::Controllers::Battery& batteryController;
diff --git a/src/displayapp/DisplayApp.cpp b/src/displayapp/DisplayApp.cpp
index a195361ddb..98be6324a9 100644
--- a/src/displayapp/DisplayApp.cpp
+++ b/src/displayapp/DisplayApp.cpp
@@ -98,11 +98,24 @@ DisplayApp::DisplayApp(Drivers::St7789& lcd,
     filesystem {filesystem},
     lvgl {lcd, filesystem},
     timer(this, TimerCallback),
-    controllers{
-      batteryController, bleController, dateTimeController, notificationManager, heartRateController,
-      settingsController, motorController, motionController, alarmController, brightnessController,
-      nullptr, filesystem, timer, nullptr, this, lvgl, nullptr, nullptr}
-  {
+    controllers {batteryController,
+                 bleController,
+                 dateTimeController,
+                 notificationManager,
+                 heartRateController,
+                 settingsController,
+                 motorController,
+                 motionController,
+                 alarmController,
+                 brightnessController,
+                 nullptr,
+                 filesystem,
+                 timer,
+                 nullptr,
+                 this,
+                 lvgl,
+                 nullptr,
+                 nullptr} {
 }
 
 void DisplayApp::Start(System::BootErrors error) {
@@ -421,8 +434,7 @@ void DisplayApp::LoadScreen(Apps app, DisplayApp::FullRefreshDirections directio
                                                                  dateTimeController,
                                                                  filesystem,
                                                                  std::move(apps));
-    }
-    break;
+    } break;
     case Apps::Clock:
       currentScreen = std::make_unique<Screens::Clock>(dateTimeController,
                                                        batteryController,
diff --git a/src/displayapp/DisplayAppRecovery.h b/src/displayapp/DisplayAppRecovery.h
index a42d3e2fb1..41aedb1793 100644
--- a/src/displayapp/DisplayAppRecovery.h
+++ b/src/displayapp/DisplayAppRecovery.h
@@ -73,7 +73,6 @@ namespace Pinetime {
       void Register(Pinetime::Controllers::MusicService* musicService);
       void Register(Pinetime::Controllers::NavigationService* NavigationService);
 
-
     private:
       TaskHandle_t taskHandle;
       static void Process(void* instance);
diff --git a/src/displayapp/UserApps.h b/src/displayapp/UserApps.h
index d0165cf9de..0ed9d60294 100644
--- a/src/displayapp/UserApps.h
+++ b/src/displayapp/UserApps.h
@@ -26,7 +26,7 @@ namespace Pinetime {
       return {AppTraits<t>::app, AppTraits<t>::icon, &AppTraits<t>::Create};
     }
 
-    template <template<Apps...> typename T, Apps ...ts>
+    template <template <Apps...> typename T, Apps... ts>
     consteval std::array<AppDescription, sizeof...(ts)> CreateAppDescriptions(T<ts...>) {
       return {CreateAppDescription<ts>()...};
     }
diff --git a/src/displayapp/screens/Alarm.h b/src/displayapp/screens/Alarm.h
index efa38eb74f..d8ed9668dc 100644
--- a/src/displayapp/screens/Alarm.h
+++ b/src/displayapp/screens/Alarm.h
@@ -65,14 +65,18 @@ namespace Pinetime {
         Widgets::Counter minuteCounter = Widgets::Counter(0, 59, jetbrains_mono_76);
       };
     }
-    template<>
+
+    template <>
     struct AppTraits<Apps::Alarm> {
       static constexpr Apps app = Apps::Alarm;
       static constexpr const char* icon = Screens::Symbols::clock;
-      static Screens::Screen *Create(AppControllers& controllers) { return new Screens::Alarm(controllers.alarmController,
+
+      static Screens::Screen* Create(AppControllers& controllers) {
+        return new Screens::Alarm(controllers.alarmController,
                                   controllers.settingsController.GetClockType(),
                                   *controllers.systemTask,
-                                  controllers.motorController); };
+                                  controllers.motorController);
+      };
     };
   }
 }
diff --git a/src/displayapp/screens/ApplicationList.cpp b/src/displayapp/screens/ApplicationList.cpp
index e5e26098d8..41735349da 100644
--- a/src/displayapp/screens/ApplicationList.cpp
+++ b/src/displayapp/screens/ApplicationList.cpp
@@ -2,7 +2,7 @@
 #include "displayapp/screens/Tile.h"
 #include <lvgl/lvgl.h>
 #include <functional>
-#include  <algorithm>
+#include <algorithm>
 #include "components/settings/Settings.h"
 
 using namespace Pinetime::Applications::Screens;
@@ -29,8 +29,8 @@ ApplicationList::ApplicationList(DisplayApp* app,
     batteryController {batteryController},
     bleController {bleController},
     dateTimeController {dateTimeController},
-    filesystem{filesystem},
-    apps{std::move(apps)},
+    filesystem {filesystem},
+    apps {std::move(apps)},
     screens {app, settingsController.GetAppMenu(), CreateScreenList(), Screens::ScreenListModes::UpDown} {
 }
 
@@ -45,8 +45,8 @@ bool ApplicationList::OnTouchEvent(Pinetime::Applications::TouchEvents event) {
 std::unique_ptr<Screen> ApplicationList::CreateScreen(unsigned int screenNum) const {
   std::array<Tile::Applications, appsPerScreen> pageApps;
 
-  for(int i = 0; i < appsPerScreen; i++) {
-    if(i+(screenNum * appsPerScreen) >= apps.size()) {
+  for (int i = 0; i < appsPerScreen; i++) {
+    if (i + (screenNum * appsPerScreen) >= apps.size()) {
       pageApps[i] = {"", Pinetime::Applications::Apps::None, false};
     } else {
       pageApps[i] = apps[i + (screenNum * appsPerScreen)];
diff --git a/src/displayapp/screens/ApplicationList.h b/src/displayapp/screens/ApplicationList.h
index 2ad9c7c717..f8a6be66ee 100644
--- a/src/displayapp/screens/ApplicationList.h
+++ b/src/displayapp/screens/ApplicationList.h
@@ -39,7 +39,7 @@ namespace Pinetime {
         static constexpr int appsPerScreen = 6;
 
         // Increment this when more space is needed
-        static constexpr int nScreens = (UserAppTypes::Count/appsPerScreen)+1;
+        static constexpr int nScreens = (UserAppTypes::Count / appsPerScreen) + 1;
 
         ScreenList<nScreens> screens;
       };
diff --git a/src/displayapp/screens/HeartRate.h b/src/displayapp/screens/HeartRate.h
index 85da8dee31..bf39209a4f 100644
--- a/src/displayapp/screens/HeartRate.h
+++ b/src/displayapp/screens/HeartRate.h
@@ -38,10 +38,12 @@ namespace Pinetime {
         lv_task_t* taskRefresh;
       };
     }
+
     template <>
     struct AppTraits<Apps::HeartRate> {
       static constexpr Apps app = Apps::HeartRate;
       static constexpr const char* icon = Screens::Symbols::heartBeat;
+
       static Screens::Screen* Create(AppControllers& controllers) {
         return new Screens::HeartRate(controllers.heartRateController, *controllers.systemTask);
       };
diff --git a/src/displayapp/screens/InfiniPaint.h b/src/displayapp/screens/InfiniPaint.h
index a25ace55a2..f7d6de535e 100644
--- a/src/displayapp/screens/InfiniPaint.h
+++ b/src/displayapp/screens/InfiniPaint.h
@@ -38,10 +38,12 @@ namespace Pinetime {
         uint8_t color = 2;
       };
     }
+
     template <>
     struct AppTraits<Apps::Paint> {
       static constexpr Apps app = Apps::Paint;
       static constexpr const char* icon = Screens::Symbols::paintbrush;
+
       static Screens::Screen* Create(AppControllers& controllers) {
         return new Screens::InfiniPaint(controllers.lvgl, controllers.motorController);
       };
diff --git a/src/displayapp/screens/Metronome.h b/src/displayapp/screens/Metronome.h
index 8820962dca..c498048ebc 100644
--- a/src/displayapp/screens/Metronome.h
+++ b/src/displayapp/screens/Metronome.h
@@ -37,10 +37,12 @@ namespace Pinetime {
         lv_task_t* taskRefresh;
       };
     }
+
     template <>
     struct AppTraits<Apps::Metronome> {
       static constexpr Apps app = Apps::Metronome;
       static constexpr const char* icon = Screens::Symbols::drum;
+
       static Screens::Screen* Create(AppControllers& controllers) {
         return new Screens::Metronome(controllers.motorController, *controllers.systemTask);
       };
diff --git a/src/displayapp/screens/Motion.h b/src/displayapp/screens/Motion.h
index 3ef570d675..9cd126f440 100644
--- a/src/displayapp/screens/Motion.h
+++ b/src/displayapp/screens/Motion.h
@@ -32,10 +32,12 @@ namespace Pinetime {
         lv_task_t* taskRefresh;
       };
     }
+
     template <>
     struct AppTraits<Apps::Motion> {
       static constexpr Apps app = Apps::Motion;
       static constexpr const char* icon = "M";
+
       static Screens::Screen* Create(AppControllers& controllers) {
         return new Screens::Motion(controllers.motionController);
       };
diff --git a/src/displayapp/screens/Music.h b/src/displayapp/screens/Music.h
index acbb63120d..062bd968af 100644
--- a/src/displayapp/screens/Music.h
+++ b/src/displayapp/screens/Music.h
@@ -85,10 +85,12 @@ namespace Pinetime {
         /** Watchapp */
       };
     }
+
     template <>
     struct AppTraits<Apps::Music> {
       static constexpr Apps app = Apps::Music;
       static constexpr const char* icon = Screens::Symbols::music;
+
       static Screens::Screen* Create(AppControllers& controllers) {
         return new Screens::Music(*controllers.musicService);
       };
diff --git a/src/displayapp/screens/Navigation.h b/src/displayapp/screens/Navigation.h
index d54df13ce3..e62745b2ca 100644
--- a/src/displayapp/screens/Navigation.h
+++ b/src/displayapp/screens/Navigation.h
@@ -58,10 +58,12 @@ namespace Pinetime {
         lv_task_t* taskRefresh;
       };
     }
+
     template <>
     struct AppTraits<Apps::Navigation> {
       static constexpr Apps app = Apps::Navigation;
       static constexpr const char* icon = Screens::Symbols::map;
+
       static Screens::Screen* Create(AppControllers& controllers) {
         return new Screens::Navigation(*controllers.navigationService);
       };
diff --git a/src/displayapp/screens/Paddle.h b/src/displayapp/screens/Paddle.h
index 0670e5b1f1..1ea2515881 100644
--- a/src/displayapp/screens/Paddle.h
+++ b/src/displayapp/screens/Paddle.h
@@ -48,10 +48,12 @@ namespace Pinetime {
         lv_task_t* taskRefresh;
       };
     }
+
     template <>
     struct AppTraits<Apps::Paddle> {
       static constexpr Apps app = Apps::Paddle;
       static constexpr const char* icon = Screens::Symbols::paddle;
+
       static Screens::Screen* Create(AppControllers& controllers) {
         return new Screens::Paddle(controllers.lvgl);
       };
diff --git a/src/displayapp/screens/Steps.h b/src/displayapp/screens/Steps.h
index 5299d67f9f..428e4b2980 100644
--- a/src/displayapp/screens/Steps.h
+++ b/src/displayapp/screens/Steps.h
@@ -42,10 +42,12 @@ namespace Pinetime {
         lv_task_t* taskRefresh;
       };
     }
+
     template <>
     struct AppTraits<Apps::Steps> {
       static constexpr Apps app = Apps::Steps;
       static constexpr const char* icon = Screens::Symbols::shoe;
+
       static Screens::Screen* Create(AppControllers& controllers) {
         return new Screens::Steps(controllers.motionController, controllers.settingsController);
       };
diff --git a/src/displayapp/screens/StopWatch.h b/src/displayapp/screens/StopWatch.h
index c3550fc41d..b3bbba8744 100644
--- a/src/displayapp/screens/StopWatch.h
+++ b/src/displayapp/screens/StopWatch.h
@@ -59,10 +59,12 @@ namespace Pinetime {
         lv_task_t* taskRefresh;
       };
     }
+
     template <>
     struct AppTraits<Apps::StopWatch> {
       static constexpr Apps app = Apps::StopWatch;
       static constexpr const char* icon = Screens::Symbols::stopWatch;
+
       static Screens::Screen* Create(AppControllers& controllers) {
         return new Screens::StopWatch(*controllers.systemTask);
       };
diff --git a/src/displayapp/screens/Timer.h b/src/displayapp/screens/Timer.h
index f8e337c2ec..409cae1cd4 100644
--- a/src/displayapp/screens/Timer.h
+++ b/src/displayapp/screens/Timer.h
@@ -10,7 +10,7 @@
 #include "components/timer/Timer.h"
 #include "Symbols.h"
 
-namespace Pinetime::Applications{
+namespace Pinetime::Applications {
   namespace Screens {
     class Timer : public Screen {
     public:
@@ -46,10 +46,13 @@ namespace Pinetime::Applications{
     };
   }
 
-  template<>
+  template <>
   struct AppTraits<Apps::Timer> {
     static constexpr Apps app = Apps::Timer;
     static constexpr const char* icon = Screens::Symbols::hourGlass;
-    static Screens::Screen *Create(AppControllers& controllers) { return new Screens::Timer(controllers.timer); };
+
+    static Screens::Screen* Create(AppControllers& controllers) {
+      return new Screens::Timer(controllers.timer);
+    };
   };
 }
diff --git a/src/displayapp/screens/Twos.h b/src/displayapp/screens/Twos.h
index 4e6980f53a..d983d13640 100644
--- a/src/displayapp/screens/Twos.h
+++ b/src/displayapp/screens/Twos.h
@@ -36,11 +36,15 @@ namespace Pinetime {
         bool placeNewTile();
       };
     }
-    template<>
+
+    template <>
     struct AppTraits<Apps::Twos> {
       static constexpr Apps app = Apps::Twos;
       static constexpr const char* icon = "2";
-      static Screens::Screen *Create(AppControllers& /*controllers*/) { return new Screens::Twos(); };
+
+      static Screens::Screen* Create(AppControllers& /*controllers*/) {
+        return new Screens::Twos();
+      };
     };
   }
 }
diff --git a/src/displayapp/screens/Weather.h b/src/displayapp/screens/Weather.h
index 888dc257cf..84177ea6fd 100644
--- a/src/displayapp/screens/Weather.h
+++ b/src/displayapp/screens/Weather.h
@@ -44,10 +44,12 @@ namespace Pinetime {
         std::unique_ptr<Screen> CreateScreenHumidity();
       };
     }
+
     template <>
     struct AppTraits<Apps::Weather> {
       static constexpr Apps app = Apps::Weather;
       static constexpr const char* icon = Screens::Symbols::sun;
+
       static Screens::Screen* Create(AppControllers& controllers) {
         return new Screens::Weather(controllers.displayApp, *controllers.weatherController);
       };

From 67fa213b30bf405bb73e4e01f9730e8d306cefa4 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Jean-Fran=C3=A7ois=20Milants?= <jf@codingfield.com>
Date: Sat, 11 Nov 2023 17:56:36 +0100
Subject: [PATCH 5/5] Application selection at build time : update
 documentation

Update documentation about the apps (Apps.md) : fix obsolete information, add doc about user/system apps and update the part about the implementation of a new app.
---
 doc/code/Apps.md | 118 +++++++++++++++++++++++++++++++++++------------
 1 file changed, 88 insertions(+), 30 deletions(-)

diff --git a/doc/code/Apps.md b/doc/code/Apps.md
index 190ad68385..714e004561 100644
--- a/doc/code/Apps.md
+++ b/doc/code/Apps.md
@@ -9,49 +9,95 @@ This page will teach you:
 
 The user interface of InfiniTime is made up of **screens**.
 Screens that are opened from the app launcher are considered **apps**.
-Every app in InfiniTime is it's own class.
+Every app in InfiniTime is its own class.
 An instance of the class is created when the app is launched, and destroyed when the user exits the app.
-Apps run inside the "displayapp" task (briefly discussed [here](./Intro.md)).
+Apps run inside the `DisplayApp` task (briefly discussed [here](./Intro.md)).
 Apps are responsible for everything drawn on the screen when they are running.
-By default, apps only do something (as in a function is executed) when they are created or when a touch event is detected.
+Apps can be refreshed periodically and reacts to external events (touch or button).
 
 ## Interface
 
-Every app class has to be inside the namespace `Pinetime::Applications::Screens` and inherit from `Screen`.
-The constructor should have at least one parameter `DisplayApp* app`, which it needs for the constructor of its parent class Screen.
-Other parameters should be references to controllers that the app needs.
-A destructor is needed to clean up LVGL and restore any changes (for example re-enable sleeping).
-App classes can override `bool OnButtonPushed()`, `bool OnTouchEvent(TouchEvents event)` and `bool OnTouchEvent(uint16_t x, uint16_t y)` to implement their own functionality for those events.
-If an app only needs to display some text and do something upon a touch screen button press,
-it does not need to override any of these functions, as LVGL can also handle touch events for you.
-If you have any doubts, you can always look at how the other apps function for reference.
+Every app class is declared inside the namespace `Pinetime::Applications::Screens` 
+and inherits
+from [`Pinetime::Applications::Screens::Screen`](https://github.com/InfiniTimeOrg/InfiniTime/blob/main/src/displayapp/screens/Screen.h).
 
-### Continuous updating
+Each app defines its own constructor.
+The constructors mostly take references to InfiniTime `Controllers` (ex: Alarm, DateTime, BLE services, Settings,...)
+the app needs for its operations. The constructor is responsible for initializing the UI of the app.
 
-If your app needs to be updated continuously, you can do so by overriding the `Refresh()` function in your class
-and calling `lv_task_create` inside the constructor.
+The **destructor** cleans up LVGL and restores any changes (for example re-enable sleeping).
 
-An example call could look like this:
+App classes can override `bool OnButtonPushed()`, `bool OnTouchEvent(TouchEvents event)`
+and `bool OnTouchEvent(uint16_t x, uint16_t y)` to implement their own functionality for those events.
 
-```cpp
-taskRefresh = lv_task_create(RefreshTaskCallback, LV_DISP_DEF_REFR_PERIOD, LV_TASK_PRIO_MID, this);
+Apps that need to be refreshed periodically create an `lv_task` (using `lv_task_create()`)
+that will call the method `Refresh()` periodically.
+
+## App types
+
+There are basically 2 types of applications : **system** apps and **user** apps.
+
+**System** applications are always built into InfiniTime, and InfiniTime cannot work properly without those apps.
+The watchfaces, settings, notifications and the application launcher are examples of such system applications.
+
+**User** applications are optionally built into the firmware. They extend the functionalities of the system.
+
+The distinction between **system** and **user** applications allows for more flexibility and customization.
+This allows to easily select which user applications must be built into the firmware
+without overflowing the system memory.
+
+## Apps initialization
+
+Apps are created by `DisplayApp` in `DisplayApp::LoadScreen()`.
+This method simply call the creates an instance of the class that corresponds to the app specified in parameters.
+
+The constructor of **system** apps is called directly. If the application is a **user** app,
+the corresponding `AppDescription` is first retrieved from `userApps`
+and then the function `create` is called to create an instance of the app.
+
+## User application selection at build time
+
+The list of user applications is generated at build time by the `consteval` function `CreateAppDescriptions()`
+in `UserApps.h`. This method takes the list of applications that must be built into the firmware image.
+This list of applications is defined as a list `Apps` enum values named `UserAppTypes` in `Apps.h`.
+For each application listed in `UserAppTypes`, an entry of type `AppDescription` is added to the array `userApps`.
+This entry is created by using the information provided by a template `AppTraits`
+that is customized for every user application.
+
+Here is an example of an AppTraits customized for the Alarm application. 
+It defines the type of application, its icon and a function that returns an instance of the application.
+
+```c++
+template <>
+struct AppTraits<Apps::Alarm> {
+  static constexpr Apps app = Apps::Alarm;
+  static constexpr const char* icon = Screens::Symbols::clock;
+
+  static Screens::Screen* Create(AppControllers& controllers) {
+    return new Screens::Alarm(controllers.alarmController,
+                              controllers.settingsController.GetClockType(),
+                              *controllers.systemTask,
+                              controllers.motorController);
+  };
+};
 ```
 
-With `taskRefresh` being a member variable of your class and of type `lv_task_t*`.
-Remember to delete the task again using `lv_task_del`.
-The function `RefreshTaskCallback` is inherited from `Screen` and just calls your `Refresh` function.
+This array `userApps` is used by `DisplayApp` to create the applications and the `AppLauncher`
+to list all available applications.
 
 ## Creating your own app
 
-A minimal app could look like this:
+A minimal user app could look like this:
 
 MyApp.h:
 
 ```cpp
 #pragma once
 
+#include "displayapp/Apps.h"
 #include "displayapp/screens/Screen.h"
-#include <lvgl/lvgl.h>
+#include "displayapp/Controllers.h"
+#include "Symbols.h"
 
 namespace Pinetime {
   namespace Applications {
@@ -62,6 +108,15 @@ namespace Pinetime {
         ~MyApp() override;
       };
     }
+    
+    template <>
+    struct AppTraits<Apps:MyApp> {
+      static constexpr Apps app = Apps::MyApp;
+      static constexpr const char* icon = Screens::Symbol::myApp;
+      static Screens::Screens* Create(AppController& controllers) {
+        return new Screens::MyApp();
+      }
+    };
   }
 }
 ```
@@ -70,7 +125,6 @@ MyApp.cpp:
 
 ```cpp
 #include "displayapp/screens/MyApp.h"
-#include "displayapp/DisplayApp.h"
 
 using namespace Pinetime::Applications::Screens;
 
@@ -86,20 +140,24 @@ MyApp::~MyApp() {
 }
 ```
 
-Both of these files should be in [displayapp/screens/](/src/displayapp/screens/)
-or [displayapp/screens/settings/](/src/displayapp/screens/settings/) if it's a setting app.
+Both of these files should be in [displayapp/screens/](/src/displayapp/screens/).
 
 Now we have our very own app, but InfiniTime does not know about it yet.
-The first step is to include your MyApp.cpp (or any new cpp files for that matter)
+The first step is to include your `MyApp.cpp` (or any new cpp files for that matter)
 in the compilation by adding it to [CMakeLists.txt](/CMakeLists.txt).
-The next step to making it launchable is to give your app an id.
+The next step to making it launch-able is to give your app an id.
 To do this, add an entry in the enum class `Pinetime::Applications::Apps` ([displayapp/Apps.h](/src/displayapp/Apps.h)).
-Name this entry after your app. Add `#include "displayapp/screens/MyApp.h"` to the file [displayapp/DisplayApp.cpp](/src/displayapp/DisplayApp.cpp).
-Now, go to the function `DisplayApp::LoadScreen` and add another case to the switch statement.
+Name this entry after your app. Add `#include "displayapp/screens/MyApp.h"`
+to the file [displayapp/DisplayApp.cpp](/src/displayapp/DisplayApp.cpp).
+
+If your application is a **system** application, go to the function `DisplayApp::LoadScreen`
+and add another case to the switch statement.
 The case will be the id you gave your app earlier.
 If your app needs any additional arguments, this is the place to pass them.
 
-If you want to add your app in the app launcher, add your app in [displayapp/screens/ApplicationList.h](/src/displayapp/screens/ApplicationList.h) to the array containing the applications and their corresponding symbol. If your app is a setting, do the same procedure in [displayapp/screens/settings/Settings.h](/src/displayapp/screens/settings/Settings.h).
+If your application is a **user** application, you don't need to add anything in DisplayApp,
+everything will be automatically generated for you.
+The user application will also be automatically be added to the app launcher menu.
 
 You should now be able to [build](../buildAndProgram.md) the firmware
 and flash it to your PineTime. Yay!