diff --git a/example.py b/example.py
index d18c887..de2bbdf 100755
--- a/example.py
+++ b/example.py
@@ -79,14 +79,18 @@ def getEvents(mail_user, mail_password, proxy):
     encoder = json.JSONEncoder()
     res = {'group':'Mail', 'items':[]}
     res['items'] += getMail(mail_user, mail_password)
-    proxy.notify(encoder.encode(res), dbus_interface='com.soutade.GenericMonitor')
+    try:
+        proxy.notify(encoder.encode(res), dbus_interface='com.soutade.GenericMonitor')
+    except dbus.exceptions.DBusException as e:
+        print(str(e))
+        pass
 
 class StockThread(Thread):
     SLEEP_TIME = 30
-    
+
     def stop(self):
         self._stopLoop = True
-        
+
     def run(self):
         self._stopLoop = False
         mail_password = getpass.getpass('Enter password for address %s: ' % (MAIL_ADDRESS))
@@ -96,14 +100,17 @@ class StockThread(Thread):
             for i in range(0, StockThread.SLEEP_TIME):
                 if self._stopLoop: break
                 time.sleep(1)
-    
+
 def signalHandler(signal_received, frame):
     stockThread.stop()
     mainLoop.quit()
     stockThread.join()
     encoder = json.JSONEncoder()
     res = {'groups':['Mail', 'Pidgin']}
-    systray_proxy.deleteGroups(encoder.encode(res), dbus_interface='com.soutade.GenericMonitor')
+    try:
+        systray_proxy.deleteGroups(encoder.encode(res), dbus_interface='com.soutade.GenericMonitor')
+    except Exception as e:
+        pass
     sys.exit(0)
 
 PURPLE_CONV_UPDATE_UNSEEN = 4
@@ -112,7 +119,7 @@ PURPLE_MESSAGE_SEND = 0
 class PidginConversation:
     STATUS_SEEN = 0
     STATUS_UNSEEN = 1
-    
+
     def __init__(self, _id):
         self._id = _id
         self.status = PidginConversation.STATUS_SEEN
@@ -134,10 +141,10 @@ class PidginConversation:
         return (self.status == PidginConversation.STATUS_SEEN)
 
 pidgin_conversations = {}
-    
+
 def pidginMessageReceived(account, sender, message, conversation, flags):
     pidginConversation = pidgin_conversations.get(conversation, None)
-    if not pidginConversation:    
+    if not pidginConversation:
         pidgin_conversations[conversation] = PidginConversation(conversation)
     else:
         pidginConversation.updateNbMessages()
@@ -146,7 +153,7 @@ def pidginMessageWrote(account, sender, message, conversation, flags):
     if not (flags & (1 << PURPLE_MESSAGE_SEND)):
         return
     pidginConversation = pidgin_conversations.get(conversation, None)
-    if not pidginConversation:    
+    if not pidginConversation:
         pidgin_conversations[conversation] = PidginConversation(conversation)
         pidginConversation = pidgin_conversations[conversation]
     pidginConversation.setSeen()
@@ -171,7 +178,11 @@ def pidginConversationUpdated(conversation, _type):
     if not pidginConversation.isSeen():
         res = {'group':'Pidgin', 'items':[]}
         res['items'] += DBUSItem('pidgin', icon='/usr/share/icons/hicolor/22x22/apps/pidgin.png', iconStyle='icon-size:22px').toMap()
-        systray_proxy.notify(encoder.encode(res), dbus_interface='com.soutade.GenericMonitor')
+        try:
+            systray_proxy.notify(encoder.encode(res), dbus_interface='com.soutade.GenericMonitor')
+        except dbus.exceptions.DBusException as e:
+            print(str(e))
+            pass
     else:
         deleteIcon = True
         # Are all messages seen ?
@@ -181,17 +192,21 @@ def pidginConversationUpdated(conversation, _type):
                 break
         if deleteIcon:
             res = {'items':['pidgin@Pidgin']}
-            systray_proxy.deleteItems(encoder.encode(res), dbus_interface='com.soutade.GenericMonitor')
-    
+            try:
+                systray_proxy.deleteItems(encoder.encode(res), dbus_interface='com.soutade.GenericMonitor')
+            except dbus.exceptions.DBusException as e:
+                print(str(e))
+                pass
+
 dbus.mainloop.glib.DBusGMainLoop(set_as_default=True)
 
 bus = dbus.SessionBus()
 systray_proxy = bus.get_object('org.gnome.Shell', '/com/soutade/GenericMonitor')
 
-bus.add_signal_receiver(pidginMessageReceived,     'ReceivedImMsg',   'im.pidgin.purple.PurpleInterface')
-bus.add_signal_receiver(pidginMessageReceived,     'ReceivedChatMsg', 'im.pidgin.purple.PurpleInterface')
-bus.add_signal_receiver(pidginMessageWrote,        'WroteImMsg',      'im.pidgin.purple.PurpleInterface')
-bus.add_signal_receiver(pidginMessageWrote,        'WroteChatMsg',    'im.pidgin.purple.PurpleInterface')
+bus.add_signal_receiver(pidginMessageReceived,     'ReceivedImMsg',       'im.pidgin.purple.PurpleInterface')
+bus.add_signal_receiver(pidginMessageReceived,     'ReceivedChatMsg',     'im.pidgin.purple.PurpleInterface')
+bus.add_signal_receiver(pidginMessageWrote,        'WroteImMsg',          'im.pidgin.purple.PurpleInterface')
+bus.add_signal_receiver(pidginMessageWrote,        'WroteChatMsg',        'im.pidgin.purple.PurpleInterface')
 bus.add_signal_receiver(pidginConversationUpdated, 'ConversationUpdated', 'im.pidgin.purple.PurpleInterface')
 
 stockThread = StockThread()
diff --git a/extension.js b/extension.js
index c2b142b..f8d8f7d 100644
--- a/extension.js
+++ b/extension.js
@@ -20,64 +20,54 @@
 
 const St = imports.gi.St;
 const Gio = imports.gi.Gio;
-const Lang = imports.lang;
 const Main = imports.ui.main;
 
 class MonitorWidget {
     constructor(name, group, text, style, icon, iconStyle) {
-	this.name = name;
-	this.group = group;
-	this._createIcon(icon, iconStyle);
-	this._createText(text, style);	
+        this.name = name;
+        this.group = group;
+        this._createIcon(icon, iconStyle);
+        this._createText(text, style);
     }
 
-    _createText(text, style)
-    {
-	this.style = style;
-	if (text == "")
-	    this.widget = null;
-	else
-	{
-	    this.widget = new St.Button({ label: text});
-	    this.widget.set_style(this.style);
-	}
+    _createText(text, style) {
+        this.style = style;
+        if (text === '') {
+            this.widget = null;
+        } else {
+            this.widget = new St.Button({ label: text });
+            this.widget.set_style(this.style);
+        }
     }
-    
-    _createIcon(icon, style)
-    {
-	this.iconStyle = style;
-	if (icon == "")
-	    this.icon = null;
-	else
-	{
-	    let gicon = Gio.icon_new_for_string(icon);
-	    this.icon = new St.Icon({ gicon });
-	    this.icon.set_style(this.iconStyle);
-	}
-    }
-    
-    update(text, style, icon, iconStyle)
-    {
-	if (!this.widget)
-	    this._createText(text, style)
-	else
-	{
-	    if (text != "")
-		this.widget.label = text;
-	    this.style = style;
-	    this.widget.set_style(this.style);
-	}
 
-	if (icon != "")
-	    this._createIcon(icon, iconStyle);
-	else
-	{
-	    if (iconStyle != "" && this.icon)
-	    {
-		this.iconStyle = style;
-		this.icon.set_style(this.iconStyle);
-	    }
-	}
+    _createIcon(icon, style) {
+        this.iconStyle = style;
+        if (icon === '') {
+            this.icon = null;
+        } else {
+            let gicon = Gio.icon_new_for_string(icon);
+            this.icon = new St.Icon({ gicon });
+            this.icon.set_style(this.iconStyle);
+        }
+    }
+
+    update(text, style, icon, iconStyle) {
+        if (!this.widget) {
+            this._createText(text, style);
+        } else {
+            if (text !== '')
+                this.widget.label = text;
+            this.style = style;
+            this.widget.set_style(this.style);
+        }
+
+        if (icon !== '')
+            this._createIcon(icon, iconStyle);
+
+        if (icon === '' && iconStyle !== '' && this.icon) {
+            this.iconStyle = style;
+            this.icon.set_style(this.iconStyle);
+        }
     }
 }
 
@@ -86,220 +76,204 @@ class MonitorWidget {
 function loadInterfaceXml(filename) {
     let extension = imports.misc.extensionUtils.getCurrentExtension();
 
-    let interfaces_dir = extension.dir.get_child(".")
+    let interfacesDir = extension.dir.get_child('.');
 
-    let file = interfaces_dir.get_child(filename);
+    let file = interfacesDir.get_child(filename);
 
-    let [ result, contents ] = imports.gi.GLib.file_get_contents(file.get_path());
+    let [result, contents] = imports.gi.GLib.file_get_contents(file.get_path());
 
     if (result) {
-        //HACK: The "" + trick is important as hell because file_get_contents returns
+        // HACK: The "" + trick is important as hell because file_get_contents returns
         // an object (WTF?) but Gio.makeProxyWrapper requires `typeof() == "string"`
         // Otherwise, it will try to check `instanceof XML` and fail miserably because there
         // is no `XML` on very recent SpiderMonkey releases (or, if SpiderMonkey is old enough,
         // will spit out a TypeError soon).
         if (contents instanceof Uint8Array)
-           contents = imports.byteArray.toString(contents);
-        return "<node>" + contents + "</node>";
+            contents = imports.byteArray.toString(contents);
+        let res = `<node>${contents}</node>`;
+        return res;
     } else {
-        throw new Error("Generic monitor: Could not load file: "+filename);
+        throw new Error(`Generic monitor: Could not load file: ${filename}`);
     }
 }
 
-const GenericMonitorDBUS = new Lang.Class({
-    Name: 'GenericMonitor',
-
-    _init: function() {
-	this.monitor_groups = {};
-	this.box = Main.panel._centerBox;
+class GenericMonitorDBUS {
+    constructor() {
+        this.monitor_groups = {};
+        this.box = Main.panel._centerBox;
         this._dbusImpl = Gio.DBusExportedObject.wrapJSObject(loadInterfaceXml('dbus.xml'), this);
         this._dbusImpl.export(Gio.DBus.session, '/com/soutade/GenericMonitor');
-    },
-
-    _checkParmeters: function(parameters)
-    {
-	if (!parameters.hasOwnProperty("group"))
-	    throw new Error("No group defined");
-
-	if (!parameters.hasOwnProperty("items"))
-	    throw new Error("No items defined");
-
-	for (let itemIndex in parameters["items"]) {
-	    let item = parameters["items"][itemIndex];
-	    if (!item.hasOwnProperty("name"))
-	    	throw new Error("No name defined for item");
-	    if (!item.hasOwnProperty("text") && !item.hasOwnProperty("icon"))
-	    	throw new Error("No text not icon defined for item");
-	}
-    },
-
-    _getItemFromGroup: function(group, name)
-    {
-	for (let groupItemIndex in group)
-	{
-	    let groupItem = group[groupItemIndex];
-	    if (groupItem.name == name)
-		return groupItem;
-	}
-
-	return null;
-    },
-    
-    notify: function(str) {
-	let parameters = JSON.parse(str);
-	this._checkParmeters(parameters);
-	
-	let groupName = parameters["group"];
-	let group;
-	if (!this.monitor_groups.hasOwnProperty(groupName))
-	{
-	    group = [];
-	    this.monitor_groups[groupName] = group;
-	}
-	else
-	    group = this.monitor_groups[groupName];
-
-	for (let itemIndex in parameters["items"]) {
-	    let item = parameters["items"][itemIndex];
-	    let style = "";
-	    if (item.hasOwnProperty("style"))
-	    	style = item["style"];
-	    let text = "";
-	    if (item.hasOwnProperty("text"))
-	    	text = item["text"];
-	    let icon = "";
-	    if (item.hasOwnProperty("icon"))
-	    	icon = item["icon"];
-	    let iconStyle = "";
-	    if (item.hasOwnProperty("icon-style"))
-	    	iconStyle = item["icon-style"];
-
-	    let monitorWidget = this._getItemFromGroup(group, item["name"]);
-	    let lastWidget = null;
-	    
-	    // New widget
-	    if (monitorWidget == null)
-	    {
-	    	monitorWidget = new MonitorWidget(item["name"], groupName, text, style, icon, iconStyle);
-	    	if (group.length)
-	    	    lastWidget = group[group.length-1].widget;
-	    	group.push(monitorWidget);
-	    	// lastWidget => NULL, insert at the end
-		if (monitorWidget.icon)
-		{
-	    	    this.box.insert_child_above(monitorWidget.icon, lastWidget);
-		    lastWidget = monitorWidget.icon;
-		}
-		if (monitorWidget.widget)
-	    	    this.box.insert_child_above(monitorWidget.widget, lastWidget);
-	    }
-	    else
-	    {
-		let prevWidget = monitorWidget.widget;
-		let prevIcon = monitorWidget.icon;
-
-	    	monitorWidget.update(text, style, icon, iconStyle);
-
-		if (monitorWidget.icon)
-		{
-		    if (prevIcon)
-			this.box.remove_child(prevIcon);
-	    	    this.box.insert_child_above(monitorWidget.icon, lastWidget);
-		    lastWidget = monitorWidget.icon;
-		}
-
-		if (!prevWidget && monitorWidget.widget)
-	    	    this.box.insert_child_above(monitorWidget.widget, lastWidget);
-	    }
-	}
-    },
-
-    _removeItemFromBox: function(item) {
-	if (item.widget)
-	    this.box.remove_child(item.widget);
-	if (item.icon)
-	    this.box.remove_child(item.icon);
-    },
-    
-    deleteItems: function(str) {
-	let parameters = JSON.parse(str);
-
-	if (!parameters.hasOwnProperty("items"))
-	    throw new Error("No items defined");
-
-	for (let itemIndex in parameters["items"]) {
-	    let itemName = parameters["items"][itemIndex];
-	    let fullName = itemName.split("@");
-	    if (fullName.length != 2)
-		throw new Error("Invalid name " + itemName);
-	    itemName = fullName[0];
-	    let groupName = fullName[1];
-	    if (!this.monitor_groups.hasOwnProperty(groupName))
-		continue;
-	    let group = this.monitor_groups[groupName];
-	    let item = this._getItemFromGroup(group, itemName);
-	    if (item != null)
-	    {
-		this._removeItemFromBox(item);
-		delete group[item["name"]];
-		if (group.length == 0)
-		    delete this.monitor_groups[groupName];
-	    }
-	}
-    },
-
-    deleteGroups: function(str) {
-	let parameters = JSON.parse(str);
-
-	if (!parameters.hasOwnProperty("groups"))
-	    throw new Error("No groups defined");
-
-	let groupsToDelete = [];
-	for (let groupIndex in parameters["groups"]) {
-	    groupName = parameters["groups"][groupIndex];
-	    if (!this.monitor_groups.hasOwnProperty(groupName))
-		continue;
-	    let group = this.monitor_groups[groupName];
-	    for (let itemIndex in group) {
-		this._removeItemFromBox(group[itemIndex]);
-	    }
-	    groupsToDelete.push(groupName);
-	}
-	for(let groupDeleteIndex in groupsToDelete)
-	{
-	    let groupName = groupsToDelete[groupDeleteIndex];
-	    delete this.monitor_groups[groupName];
-	}
-    },
-
-    deleteAll: function() {
-	for (let groupIndex in this.monitor_groups) {
-	    let group = this.monitor_groups[groupIndex];
-	    for (let itemIndex in group) {
-		this._removeItemFromBox(group[itemIndex]);
-	    }
-	}	    
-	this.monitor_groups = {}
-    },
-});
-
-class Extension {
-    constructor() {
-	this.textDBusService = new GenericMonitorDBUS();
     }
 
+    _checkParmeters(parameters) {
+        if (!parameters.hasOwnProperty('group'))
+            throw new Error('No group defined');
+
+        if (!parameters.hasOwnProperty('items'))
+            throw new Error('No items defined');
+
+        for (let itemIndex in parameters['items']) {
+            let item = parameters['items'][itemIndex];
+            if (!item.hasOwnProperty('name'))
+                throw new Error('No name defined for item');
+            if (!item.hasOwnProperty('text') && !item.hasOwnProperty('icon'))
+                throw new Error('No text not icon defined for item');
+        }
+    }
+
+    _getItemFromGroup(group, name) {
+        for (let groupItemIndex in group) {
+            let groupItem = group[groupItemIndex];
+            if (groupItem.name === name)
+                return groupItem;
+        }
+
+        return null;
+    }
+
+    notify(str) {
+        let parameters = JSON.parse(str);
+        this._checkParmeters(parameters);
+
+        let groupName = parameters['group'];
+        let group;
+        if (!this.monitor_groups.hasOwnProperty(groupName)) {
+            group = [];
+            this.monitor_groups[groupName] = group;
+        } else {
+            group = this.monitor_groups[groupName];
+        }
+
+        for (let itemIndex in parameters['items']) {
+            let item = parameters['items'][itemIndex];
+            let style = '';
+            if (item.hasOwnProperty('style'))
+                style = item['style'];
+            let text = '';
+            if (item.hasOwnProperty('text'))
+                text = item['text'];
+            let icon = '';
+            if (item.hasOwnProperty('icon'))
+                icon = item['icon'];
+            let iconStyle = '';
+            if (item.hasOwnProperty('icon-style'))
+                iconStyle = item['icon-style'];
+
+            let monitorWidget = this._getItemFromGroup(group, item['name']);
+            let lastWidget = null;
+
+            // New widget
+            if (monitorWidget === null) {
+                monitorWidget = new MonitorWidget(item['name'], groupName, text, style, icon, iconStyle);
+                if (group.length)
+                    lastWidget = group[group.length - 1].widget;
+                group.push(monitorWidget);
+                // lastWidget => NULL, insert at the end
+                if (monitorWidget.icon) {
+                    this.box.insert_child_above(monitorWidget.icon, lastWidget);
+                    lastWidget = monitorWidget.icon;
+                }
+                if (monitorWidget.widget)
+                    this.box.insert_child_above(monitorWidget.widget, lastWidget);
+            } else {
+                let prevWidget = monitorWidget.widget;
+                let prevIcon = monitorWidget.icon;
+
+                monitorWidget.update(text, style, icon, iconStyle);
+
+                if (monitorWidget.icon) {
+                    if (prevIcon)
+                        this.box.remove_child(prevIcon);
+                    this.box.insert_child_above(monitorWidget.icon, lastWidget);
+                    lastWidget = monitorWidget.icon;
+                }
+
+                if (!prevWidget && monitorWidget.widget)
+                    this.box.insert_child_above(monitorWidget.widget, lastWidget);
+            }
+        }
+    }
+
+    _removeItemFromBox(item) {
+        if (item.widget)
+            this.box.remove_child(item.widget);
+        if (item.icon)
+            this.box.remove_child(item.icon);
+    }
+
+    deleteItems(str) {
+        let parameters = JSON.parse(str);
+
+        if (!parameters.hasOwnProperty('items'))
+            throw new Error('No items defined');
+
+        for (let itemIndex in parameters['items']) {
+            let itemName = parameters['items'][itemIndex];
+            let fullName = itemName.split('@');
+            if (fullName.length !== 2)
+                throw new Error(`Invalid name ${itemName}`);
+            itemName = fullName[0];
+            let groupName = fullName[1];
+            if (!this.monitor_groups.hasOwnProperty(groupName))
+                continue;
+            let group = this.monitor_groups[groupName];
+            let item = this._getItemFromGroup(group, itemName);
+            if (item !== null) {
+                this._removeItemFromBox(item);
+                delete group[item['name']];
+                if (group.length === 0)
+                    delete this.monitor_groups[groupName];
+            }
+        }
+    }
+
+    deleteGroups(str) {
+        let parameters = JSON.parse(str);
+
+        if (!parameters.hasOwnProperty('groups'))
+            throw new Error('No groups defined');
+
+        let groupsToDelete = [];
+        for (let groupIndex in parameters['groups']) {
+            let groupName = parameters['groups'][groupIndex];
+            if (!this.monitor_groups.hasOwnProperty(groupName))
+                continue;
+            let group = this.monitor_groups[groupName];
+            for (let itemIndex in group)
+                this._removeItemFromBox(group[itemIndex]);
+            groupsToDelete.push(groupName);
+        }
+        for (let groupDeleteIndex in groupsToDelete) {
+            let groupName = groupsToDelete[groupDeleteIndex];
+            delete this.monitor_groups[groupName];
+        }
+    }
+
+    destructor() {
+        for (let groupIndex in this.monitor_groups) {
+            let group = this.monitor_groups[groupIndex];
+            for (let itemIndex in group)
+                this._removeItemFromBox(group[itemIndex]);
+        }
+        this.monitor_groups = {};
+        this._dbusImpl.unexport();
+    }
+}
+
+class Extension {
     enable() {
+        this.textDBusService = new GenericMonitorDBUS();
     }
 
     disable() {
-	this.textDBusService.deleteAll();
+        this.textDBusService.destructor();
+        delete this.textDBusService;
     }
 }
 
-let extension = null;
+let extension = new Extension();
 
 function init() {
-    extension = new Extension();
 }
 
 function enable() {