diff --git a/.github/labeler.yml b/.github/labeler.yml
index 972b28d350..2e50dbdd35 100644
--- a/.github/labeler.yml
+++ b/.github/labeler.yml
@@ -9,7 +9,6 @@ Building:
     - .github/**
     - CMakeLists.txt
     - builds/**
-    - '!builds/android/app/**'
     - Makefile.am
     - configure.ac
 
@@ -37,6 +36,22 @@ Audio:
 - changed-files:
   - any-glob-to-any-file: [ src/**/*audio* ]
 
+Battle:
+- changed-files:
+  - any-glob-to-any-file:
+    - src/**/scene_battle*
+    - src/**/window_battle*
+    - src/**/game_battle.*
+    - src/**/game_battlealgorithm.*
+
+Bitmaps:
+- changed-files:
+  - any-glob-to-any-file:
+    - src/**/bitmap.*
+    - src/**/bitmap_*
+    - src/**/sprite.*
+    - src/**/sprite_*
+
 FileFinder:
 - changed-files:
   - any-glob-to-any-file: [ src/**/filefinder*, src/**/filesystem* ]
@@ -51,10 +66,26 @@ Fonts:
     - src/**/*font*
     - src/generated/bitmapfont_*
 
+Input:
+- changed-files:
+  - any-glob-to-any-file: [ src/**/*input* ]
+
+Messages:
+- changed-files:
+  - any-glob-to-any-file: [ src/**/*message* ]
+
 MIDI:
 - changed-files:
   - any-glob-to-any-file: [ src/**/*midi* ]
 
+Settings:
+- changed-files:
+  - any-glob-to-any-file: [ src/**/*config* ]
+
+Translation:
+- changed-files:
+  - any-glob-to-any-file: [ src/**/translation* ]
+
 # platforms
 
 3DS:
diff --git a/CMakeLists.txt b/CMakeLists.txt
index 48b917b7a4..f63d4ffa55 100644
--- a/CMakeLists.txt
+++ b/CMakeLists.txt
@@ -73,6 +73,7 @@ add_library(${PROJECT_NAME} OBJECT
 	src/bitmap_hslrgb.h
 	src/cache.cpp
 	src/cache.h
+	src/callback.h
 	src/cmdline_parser.cpp
 	src/cmdline_parser.h
 	src/color.h
diff --git a/Makefile.am b/Makefile.am
index 7ee65f6792..b61c8d6fb8 100644
--- a/Makefile.am
+++ b/Makefile.am
@@ -51,6 +51,7 @@ libeasyrpg_player_a_SOURCES = \
 	src/bitmap_hslrgb.h \
 	src/cache.cpp \
 	src/cache.h \
+	src/callback.h \
 	src/cmdline_parser.cpp \
 	src/cmdline_parser.h \
 	src/color.h \
diff --git a/src/callback.h b/src/callback.h
new file mode 100644
index 0000000000..1840fd38d1
--- /dev/null
+++ b/src/callback.h
@@ -0,0 +1,157 @@
+/*
+ * This file is part of EasyRPG Player.
+ *
+ * EasyRPG Player is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation, either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * EasyRPG Player is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with EasyRPG Player. If not, see <http://www.gnu.org/licenses/>.
+ */
+
+#ifndef EP_CALLBACK_H
+#define EP_CALLBACK_H
+
+#include <lcf/scope_guard.h>
+#include <vector>
+#include <functional>
+#include <utility>
+#include <algorithm>
+
+#if 0
+Where to place a callback:
+When it is related to something global put the callback where it is suitable.
+When it is related to an instance of a class/struct add it as a public variable.
+
+Adding a new callback:
+
+Assuming you want to add a notification when a variable is changed.
+
+In the header of Game_Variables (game_variables.h) add a public field
+
+```cpp
+Callback<int /* variable_id */, int /* value */> OnVariableChanged;
+```
+
+The /* names */ are for increated readability.
+Functions that take two integer arguments can be bound to this callback.
+
+Signal the callback at a suitable location.
+Here this would be in SetOp in game_variables.cpp:
+
+```cpp
+OnVariableChanged.Call(variable_id, v);
+```
+
+This invocation will trigger all functions attached with Bind.
+
+Attaching to the callback:
+
+```cpp
+// Attaching with a scope guard (the callback will automatically Unbind when the
+// guard is not in scope anymore).
+// This prevents stale handlers that crash.
+auto guard = Main_Data::game_variables->OnVariableChanged.Bind([](int var_id, int val) {
+	Output::Warning("{} = {}", var_id, val);
+});
+
+// In case of a class the scope guard should be a field.
+// It is automatically unbound when the instance is destroyed.
+class MyClass {
+public:
+	MyClass() {
+		guard = Main_Data::game_variables->OnVariableChanged.Bind([](int var_id, int val) {
+			Output::Warning("{} = {}", var_id, val);
+		});
+
+		// Alternative: Binding a method instead of a lambda
+		guard = Main_Data::game_variables->OnVariableChanged.Bind(&MyClass::VariableChanged, this);
+	}
+
+	void VariableChanged(int var_id, int val) {
+		Output::Warning("{} = {}", var_id, val);
+	}
+
+private:
+	BindingScopeGuard guard;
+}
+```
+
+Not recommended:
+
+If you want to (for whatever reason) manually manage the lifetime of the binding
+use BindUnmanaged.
+
+This works the same as described above but the function returns an integer.
+
+And you must that integer to Unbind(id) to remove the handler.
+#endif
+
+using BindingScopeGuard = lcf::ScopeGuard<std::function<void()>>;
+
+template</*typename Ret, */typename ...Args>
+class Callback {
+public:
+	using Ret = void;
+	using Fn = std::function<Ret(Args...)>;
+
+	template<typename T>
+	int BindUnmanaged(Ret (T::*func)(Args...), T* that, Args... args) {
+		Fn f = std::bind(std::mem_fn(func), that, std::placeholders::_1, args...);
+		return BindUnmanaged(f);
+	}
+
+	int BindUnmanaged(Fn func) {
+		listeners.push_back({next_id, func});
+		return next_id++;
+	}
+
+	template<typename T>
+	BindingScopeGuard Bind(Ret (T::*func)(Args...), T* that, Args... args) {
+		int id = BindUnmanaged(func, that, args...);
+
+		return lcf::ScopeGuard<std::function<void()>>([this, id=id]() {
+			Unbind(id);
+		});
+	}
+
+	BindingScopeGuard Bind(Fn func) {
+		int id = BindUnmanaged(func);
+
+		return lcf::ScopeGuard<std::function<void()>>([this, id]() {
+			Unbind(id);
+		});
+	}
+
+	void Unbind(int id) {
+		auto it = std::find_if(listeners.begin(), listeners.end(), [id](auto& listener){
+			return listener.first == id;
+		});
+		assert(it != listeners.end());
+
+		listeners.erase(it);
+	}
+
+	void Call(Args... args) {
+		for (auto& listener: listeners) {
+			listener.second(std::forward<Args>(args)...);
+		}
+	}
+
+	void Clear() {
+		listeners.clear();
+	}
+
+private:
+	std::vector<std::pair<int, Fn>> listeners;
+
+	int next_id = 1;
+};
+
+#endif
diff --git a/src/player.cpp b/src/player.cpp
index 494f09a052..eedb575968 100644
--- a/src/player.cpp
+++ b/src/player.cpp
@@ -16,7 +16,6 @@
  */
 
 // Headers
-
 #include <algorithm>
 #include <cstring>
 #include <cstdlib>
@@ -81,6 +80,7 @@
 #include "instrumentation.h"
 #include "transition.h"
 #include <lcf/scope_guard.h>
+#include <lcf/log_handler.h>
 #include "baseui.h"
 #include "game_clock.h"
 #include "message_overlay.h"
@@ -152,6 +152,10 @@ namespace {
 }
 
 void Player::Init(std::vector<std::string> args) {
+	lcf::LogHandler::SetHandler([](lcf::LogHandler::Level level, StringView message, lcf::LogHandler::UserData) {
+		Output::Debug("lcf ({}): {}", lcf::LogHandler::kLevelTags.tag(level), message);
+	});
+
 	frames = 0;
 
 	// Must be called before the first call to Output