Add settings_changed signal to ProjectSettings

core/config/project_settings.cpp

@@ -283,6 +283,7 @@ bool ProjectSettings::_set(const StringName &p_name, const Variant &p_value) {
 			for (int i = 0; i < custom_feature_array.size(); i++) {
 				custom_features.insert(custom_feature_array[i]);
 			}
+			_queue_changed();
 			return true;
 		}
 
@@ -324,6 +325,7 @@ bool ProjectSettings::_set(const StringName &p_name, const Variant &p_value) {
 		}
 	}
 
+	_queue_changed();
 	return true;
 }
 
@@ -424,6 +426,22 @@ void ProjectSettings::_get_property_list(List<PropertyInfo> *p_list) const {
 	}
 }
 
+void ProjectSettings::_queue_changed() {
+	if (is_changed || !MessageQueue::get_singleton() || MessageQueue::get_singleton()->get_max_buffer_usage() == 0) {
+		return;
+	}
+	is_changed = true;
+	callable_mp(this, &ProjectSettings::_emit_changed).call_deferred();
+}
+
+void ProjectSettings::_emit_changed() {
+	if (!is_changed) {
+		return;
+	}
+	is_changed = false;
+	emit_signal("settings_changed");
+}
+
 bool ProjectSettings::_load_resource_pack(const String &p_pack, bool p_replace_files, int p_offset) {
 	if (PackedData::get_singleton()->is_disabled()) {
 		return false;
@@ -1225,6 +1243,8 @@ void ProjectSettings::_bind_methods() {
 	ClassDB::bind_method(D_METHOD("load_resource_pack", "pack", "replace_files", "offset"), &ProjectSettings::_load_resource_pack, DEFVAL(true), DEFVAL(0));
 
 	ClassDB::bind_method(D_METHOD("save_custom", "file"), &ProjectSettings::_save_custom_bnd);
+
+	ADD_SIGNAL(MethodInfo("settings_changed"));
 }
 
 void ProjectSettings::_add_builtin_input_map() {

core/config/project_settings.h

@@ -45,6 +45,8 @@ class ProjectSettings : public Object {
 	_THREAD_SAFE_CLASS_
 	friend class TestProjectSettingsInternalsAccessor;
 
+	bool is_changed = false;
+
 public:
 	typedef HashMap<String, Variant> CustomMap;
 	static const String PROJECT_DATA_DIR_NAME_SUFFIX;
@@ -115,6 +117,9 @@ protected:
 	bool _property_can_revert(const StringName &p_name) const;
 	bool _property_get_revert(const StringName &p_name, Variant &r_property) const;
 
+	void _queue_changed();
+	void _emit_changed();
+
 	static ProjectSettings *singleton;
 
 	Error _load_settings_text(const String &p_path);

doc/classes/ProjectSettings.xml

@@ -2710,4 +2710,11 @@
 			If [code]true[/code], Godot will compile shaders required for XR.
 		</member>
 	</members>
+	<signals>
+		<signal name="settings_changed">
+			<description>
+				Emitted when any setting is changed, up to once per process frame.
+			</description>
+		</signal>
+	</signals>
 </class>