diff --git a/data/inject.js b/data/inject.js
index d5867e5..b2f32a2 100644
--- a/data/inject.js
+++ b/data/inject.js
@@ -10,6 +10,7 @@
 	};
 	var blockMode = {
 		getContext: {
+			name: "getContext",
 			status: "block",
 			askText: {
 				visible: "askForVisiblePermission",
@@ -23,6 +24,7 @@
 			}
 		},
 		readAPI: {
+			name: "readAPI",
 			status: "allow",
 			askText: {
 				visible: "askForVisibleReadoutPermission",
@@ -196,6 +198,7 @@
 							appearance.reset();
 						}
 					}
+					self.port.emit("accessed " + changedFunction.mode.name, status);
 					switch (status){
 						case "allow":
 							return original;
@@ -242,7 +245,7 @@
 	// Communication with main.js
 	
 	function checkAbout(){
-		return document.location.protocol === "about:");
+		return document.location.protocol === "about:";
 	}
 	
 	function checkPDF(blocking){
diff --git a/lib/main.js b/lib/main.js
index ee39930..9bf67fd 100644
--- a/lib/main.js
+++ b/lib/main.js
@@ -48,6 +48,7 @@
 	var pageMod = require("sdk/page-mod");
 	var array = require("sdk/util/array");
 	var preferences = require("sdk/simple-prefs");
+	var prefService = require("sdk/preferences/service");
 	var prefs = preferences.prefs;
 	var URL = require("sdk/url").URL;
 	var _ = require("sdk/l10n").get;
@@ -87,7 +88,7 @@
 	});
 	
 	function checkURL(url){
-		var url = new URL(url);
+		url = new URL(url);
 		var mode = "block";
 		switch (prefs.blockMode){
 			case "blockEverything":
@@ -180,6 +181,56 @@
 			});
 			
 			checkWorker(worker);
+			
+			// display notifications
+			worker.port.on("accessed readAPI", function(status){
+				switch (status){
+					case "fake":
+						var contentURL = new URL(worker.contentURL);
+						var url = contentURL.href;
+						var domain = contentURL.hostname;
+						var message = "Faked readout on " + url;
+						
+						
+						var notifyBox = gWindow.getNotificationBox();
+						var notification = notifiyBox.getNotificationBoxWithValue("fake-readout");
+						if (notification){
+							notification.label = message;
+						}
+						else {
+							var buttons = [
+								{
+									label: 'whitelist URL',
+									callback: function(){
+										prefs.whiteList += "," + url;
+										prefService.set("extensions.CanvasBlocker@kkapsner.de.whiteList", prefs.whiteList);
+										updateWhiteList();
+										workers.forEach(checkWorker);
+									}
+								},
+								{
+									label: 'whitelist domain',
+									callback: function(){
+										prefs.whiteList += "," + domain;
+										prefService.set("extensions.CanvasBlocker@kkapsner.de.whiteList", prefs.whiteList);
+										updateWhiteList();
+										workers.forEach(checkWorker);
+									}
+								}
+							];
+
+							let priority = box.PRIORITY_WARNING_MEDIUM;
+							box.appendNotification(
+								message,
+								'fake-readout',
+								'chrome://browser/skin/Info.png',
+								priority,
+								buttons
+							);
+						}
+						break;
+				}
+			});
 		},
 	});
 
diff --git a/package.json b/package.json
index 5ec46bb..1c51a66 100644
--- a/package.json
+++ b/package.json
@@ -20,7 +20,7 @@
 			"name": "blockMode",
 			"title": "block mode",
 			"type": "menulist",
-			"value": "askReadout",
+			"value": "fakeReadout",
 			"options": [
 				{
 					"value": "blockEverything",