diff --git a/.tools/findUnusedMessages.js b/.tools/findUnusedMessages.js
new file mode 100644
index 0000000..b970993
--- /dev/null
+++ b/.tools/findUnusedMessages.js
@@ -0,0 +1,146 @@
+const fs = require("fs");
+const path = require("path");
+const util = require("util");
+
+
+
+function getMessagesInContent(content){
+	const foundMessages = [];
+	[
+		/\b(?:_|browser.i18n.getMessage|notify)\(["']([^"']+)["']\s*(?:\)|,)/g,
+		/\b(?:messageId|name)\s*:\s*["']([^"']+)["']/g,
+	].forEach(function(re){
+		let match;
+		while ((match = re.exec(content)) !== null){
+			foundMessages.push(match[1].toLowerCase());
+		}
+	});
+	return foundMessages;
+}
+
+async function getMessagesInFile(path){
+	return await util.promisify(fs.exists)(path)
+	.then(function(exists){
+		if (exists){
+			return util.promisify(fs.readFile)(path, {encoding: "UTF-8"})
+			.then(function(content){
+				return getMessagesInContent(content);
+			});
+		}
+		else {
+			console.log("file does not exist:", path);
+			return [];
+		}
+	});
+}
+
+async function getMessagesInFolder(folder){
+	return await util.promisify(fs.readdir)(folder, {encoding: "UTF-8"})
+	.then(function(files){
+		return Promise.all(
+			files.filter(function(file){
+				return !file.startsWith(".");
+			}).map(function(file){
+				return path.join(folder, file);
+			}).map(function(path){
+				return util.promisify(fs.stat)(path).then(function(stat){
+					if (stat.isDirectory()){
+						return getMessagesInFolder(path);
+					}
+					else {
+						if (path.endsWith(".js")){
+							return getMessagesInFile(path);
+						}
+						else {
+							return [];
+						}
+					}
+				});
+			})
+		).then(function(messages){
+			const flat = [];
+			messages.forEach(function(messages){
+				messages.forEach(function(message){
+					flat.push(message);
+				});
+			});
+			return flat;
+		});
+	})
+}
+
+
+async function getSettingMessages(){ 
+	const settingStrings = require("../lib/settingStrings");
+	const settingDefinitions = require("../lib/settingDefinitions");
+	function getDefinition(name){
+		return settingDefinitions.filter(function(settingDefinition){
+			return settingDefinition.name === name;
+		})[0];
+	}
+	const settingsDisplay = require("../options/settingsDisplay");
+
+	const foundMessages = [];
+	settingsDisplay.forEach(function(display){
+		if ((typeof display) === "string"){
+			foundMessages.push("section_" + display.toLowerCase());
+		}
+		else {
+			let settingDefinition = getDefinition(display.name);
+			if (!settingDefinition){
+				settingDefinition = display;
+				display.action = true;
+			}
+			if (settingDefinition){
+				if (display.inputs){
+					settingDefinition.inputs = display.inputs.map(function(input){
+						return getDefinition(input);
+					});
+				}
+				else if (display.actions){
+					settingDefinition.actions = display.actions.map(function(action){
+						return {name: action};
+					});
+				}
+				settingStrings.getMessages(settingDefinition).forEach(function(message){
+					foundMessages.push(message.toLowerCase());
+				});
+			}
+		}
+	});
+	return foundMessages.map(function(message){return message.toLowerCase();});
+}
+
+async function getKnownMessages(){
+	return [
+		"addon_title",
+		"addon_description",
+		"urlsettings_title",
+		"installnotice",
+		"updatenotice",
+		"disablenotifications",
+		"showoptions",
+		"displayhiddensettings_title",
+		"displayhiddensettings_description",
+		"browseraction_settings",
+		"browseraction_test",
+		"browseraction_review",
+		"browseraction_reportissue",
+	];
+}
+
+const en = require("../_locales/en/messages.json");
+const declaredMessages = Object.keys(en)
+	// .filter(function(key){return en[key].message;})
+	.map(function(key){return key.toLowerCase();});
+Promise.all([getSettingMessages(), getMessagesInFolder(path.join(__dirname, "..")), getKnownMessages()]).then(function([settingMessages, fileMessages, knownMessages]){
+	declaredMessages.forEach(function(message){
+		if (
+			fileMessages.indexOf(message) === -1 &&
+			settingMessages.indexOf(message) === -1 &&
+			knownMessages.indexOf(message) === -1
+		){
+			console.log(`${message} not used`);
+		}
+	});
+});
\ No newline at end of file
diff --git a/_locales/de/messages.json b/_locales/de/messages.json
index 2b065b9..1acdaab 100644
--- a/_locales/de/messages.json
+++ b/_locales/de/messages.json
@@ -154,14 +154,6 @@
 		"description": ""
 	},
 	
-	"allowPDFCanvas_description": {
-		"message": "Die native pdf.js verwendet <canvas> um den Inhalt von PDFs anzuzeigen. Wenn viele Nachfragedialoge erscheinen oder die PDF-Ansicht nicht funktioniert, müssen diese erlaubt werden.",
-		"description": ""
-	},
-	"allowPDFCanvas_title": {
-		"message": "<canvas> in PDFs erlauben",
-		"description": ""
-	},
 	"askForInvisiblePermission": {
 		"message": "Wollen Sie unsichtbare <canvas> erlauben?",
 		"description": ""
@@ -363,14 +355,6 @@
 		"description": ""
 	},
 	
-	"url_title": {
-		"message": "URL",
-		"description": ""
-	},
-	"url_description": {
-		"message": "",
-		"description": ""
-	},
 	"inputURL": {
 		"message": "Domain oder URL \"RegExp\" eingeben:",
 		"description": ""
@@ -824,10 +808,6 @@
 		"description": ""
 	},
 	
-	"inspectImage": {
-		"message": "Bild betrachten",
-		"description": ""
-	},
 	"storeImageForInspection_title": {
 		"message": "Bild für Betrachtung speichern",
 		"description": ""
diff --git a/_locales/en/messages.json b/_locales/en/messages.json
index d1bd605..f6d8ceb 100644
--- a/_locales/en/messages.json
+++ b/_locales/en/messages.json
@@ -355,14 +355,6 @@
 		"description": ""
 	},
 	
-	"url_title": {
-		"message": "URL",
-		"description": ""
-	},
-	"url_description": {
-		"message": "",
-		"description": ""
-	},
 	"inputURL": {
 		"message": "Input domain or URL \"RegExp\":",
 		"description": ""
@@ -743,14 +735,6 @@
 		"message": "blink",
 		"description": ""
 	},
-	"notificationDisplayTime_description": {
-		"message": "Number of seconds the notifications are shown. (Enter zero to disable automatic closing.)",
-		"description": ""
-	},
-	"notificationDisplayTime_title": {
-		"message": "Notification display time",
-		"description": ""
-	},
 	"sourceOutput": {
 		"message": "Calling file",
 		"description": ""
@@ -823,10 +807,6 @@
 		"description": ""
 	},
 	
-	"inspectImage": {
-		"message": "inspect image",
-		"description": ""
-	},
 	"storeImageForInspection_title": {
 		"message": "Store image for inspection",
 		"description": ""
diff --git a/_locales/es/messages.json b/_locales/es/messages.json
index b02772c..f63291b 100644
--- a/_locales/es/messages.json
+++ b/_locales/es/messages.json
@@ -121,14 +121,6 @@
 		"description": ""
 	},
 	
-	"allowPDFCanvas_description": {
-		"message": "El lector de PDF integrado de Firefox usa la API para mostrar el contenido de los PDF. Si aparecen demasiados cuadros de diálogo o si no funciona el lector de PDF en absoluto, tiene que permitir esto.",
-		"description": ""
-	},
-	"allowPDFCanvas_title": {
-		"message": "Permitir canvas en los PDF",
-		"description": ""
-	},
 	"askForInvisiblePermission": {
 		"message": "¿Quiere permitir los <canvas> invisibles?",
 		"description": ""
@@ -290,14 +282,6 @@
 		"description": ""
 	},
 	
-	"url_title": {
-		"message": "URL",
-		"description": ""
-	},
-	"url_description": {
-		"message": "",
-		"description": ""
-	},
 	"inputURL": {
 		"message": "Introduzca un dominio o RegExp de URL:",
 		"description": ""
@@ -681,10 +665,6 @@
 		"description": ""
 	},
 	
-	"inspectImage": {
-		"message": "inspeccionar la imagen",
-		"description": ""
-	},
 	"storeImageForInspection_title": {
 		"message": "Guardar la imagen para inspeccionarla",
 		"description": ""
diff --git a/_locales/fr/messages.json b/_locales/fr/messages.json
index 4cdd3c9..0515c21 100644
--- a/_locales/fr/messages.json
+++ b/_locales/fr/messages.json
@@ -100,14 +100,6 @@
 		"description": ""
 	},
 	
-	"allowPDFCanvas_description": {
-		"message": "Le fichier pdf.js (JavaScript) utilise <canvas> pour afficher le contenu des PDF. Si de nombreuses boîtes de dialogue apparaissent ou si la vue de PDF ne fonctionne pas, canvas doit être autorisé.",
-		"description": ""
-	},
-	"allowPDFCanvas_title": {
-		"message": "Autoriser Canvas dans les fichiers PDF",
-		"description": ""
-	},
 	"askForInvisiblePermission": {
 		"message": "Voulez-vous autoriser l'utilisation de <canvas> invisible ?",
 		"description": ""
@@ -269,14 +261,6 @@
 		"description": ""
 	},
 	
-	"url_title": {
-		"message": "URL",
-		"description": ""
-	},
-	"url_description": {
-		"message": "",
-		"description": ""
-	},
 	"inputURL": {
 		"message": "Input domain or URL RegExp:",
 		"description": ""
@@ -577,10 +561,6 @@
 		"description": ""
 	},
 	
-	"inspectImage": {
-		"message": "Visionner l'image",
-		"description": ""
-	},
 	"storeImageForInspection_title": {
 		"message": "Enregistrer l'image pour la visualiser",
 		"description": ""
diff --git a/_locales/it/messages.json b/_locales/it/messages.json
index ec14597..7d2a873 100644
--- a/_locales/it/messages.json
+++ b/_locales/it/messages.json
@@ -35,14 +35,6 @@
 		"description": ""
 	},
 	
-	"allowPDFCanvas_description": {
-		"message": "Il lettore PDF nativo di Firefox usa le API per visualizzare i PDF. Se compaiono troppe finestre di interazione o il lettore PDF non funziona proprio, allora devono essere permesse.",
-		"description": ""
-	},
-	"allowPDFCanvas_title": {
-		"message": "Permetti canvas nei PDF",
-		"description": ""
-	},
 	"askForInvisiblePermission": {
 		"message": "Vuoi permettere i <canvas> invisibili?",
 		"description": ""
@@ -178,14 +170,6 @@
 		"description": ""
 	},
 	
-	"url_title": {
-		"message": "URL",
-		"description": ""
-	},
-	"url_description": {
-		"message": "",
-		"description": ""
-	},
 	"inputURL": {
 		"message": "Inserisci dominio o RegExp URL:",
 		"description": ""
@@ -465,10 +449,6 @@
 		"description": ""
 	},
 	
-	"inspectImage": {
-		"message": "ispeziona immagine",
-		"description": ""
-	},
 	"storeImageForInspection_title": {
 		"message": "Memorizza immagine per ispezione",
 		"description": ""
diff --git a/_locales/zh_CN/messages.json b/_locales/zh_CN/messages.json
index 019ab35..149782f 100644
--- a/_locales/zh_CN/messages.json
+++ b/_locales/zh_CN/messages.json
@@ -100,14 +100,6 @@
 		"description": ""
 	},
 	
-	"allowPDFCanvas_description": {
-		"message": "Firefox 自带的 PDF 阅读器（pdf.js）使用该 API 显示 PDF 内容。如果出现了太多的询问对话框，或者 PDF 阅读器功能失效，则您需要在对话框中允许。",
-		"description": ""
-	},
-	"allowPDFCanvas_title": {
-		"message": "允许 PDF 文件中的 Canvas",
-		"description": ""
-	},
 	"askForInvisiblePermission": {
 		"message": "是否允许不可见的 <canvas>？",
 		"description": ""
@@ -269,14 +261,6 @@
 		"description": ""
 	},
 	
-	"url_title": {
-		"message": "URL",
-		"description": ""
-	},
-	"url_description": {
-		"message": "",
-		"description": ""
-	},
 	"inputURL": {
 		"message": "输入域名或网址（URL）的正则表达式：",
 		"description": ""
@@ -603,10 +587,6 @@
 		"description": ""
 	},
 	
-	"inspectImage": {
-		"message": "察看图像",
-		"description": ""
-	},
 	"storeImageForInspection_title": {
 		"message": "存储图像以备察看",
 		"description": ""