diff --git a/content/events.js b/content/events.js
index d1fd8cec..b6af87c6 100644
--- a/content/events.js
+++ b/content/events.js
@@ -307,8 +307,8 @@ liberator.Events = function () //{{{
     }
     function exitPopupMode()
     {
-        // gContextMenu is set to NULL by firefox, when a context menu is closed
-        if (!gContextMenu && !activeMenubar)
+        // gContextMenu is set to NULL by Firefox, when a context menu is closed
+        if (typeof gContextMenu != "undefined" && gContextMenu == NULL && !activeMenubar)
             liberator.modes.remove(liberator.modes.MENU);
     }
     function enterMenuMode()
@@ -662,7 +662,8 @@ liberator.Events = function () //{{{
             // removeEventListeners() to avoid mem leaks
             window.dump("TODO: remove all eventlisteners\n");
 
-            getBrowser().removeProgressListener(this.progressListener);
+            if (typeof(getBrowser) != "undefined")
+                getBrowser().removeProgressListener(this.progressListener);
 
             window.removeEventListener("popupshown", enterPopupMode, true);
             window.removeEventListener("popuphidden", exitPopupMode, true);
diff --git a/content/liberator.js b/content/liberator.js
index 4b8f5da9..bd558ede 100644
--- a/content/liberator.js
+++ b/content/liberator.js
@@ -72,28 +72,6 @@ const liberator = (function () //{{{
                 }
             });
 
-        liberator.options.add(["titlestring"], // TODO: broken for Thunderbird
-            "Change the title of the window",
-            "string", "Vimperator",
-            {
-                setter: function (value)
-                {
-                    try
-                    {
-                        var id = liberator.config.mainWindowID || "main-window";
-                        document.getElementById(id).setAttribute("titlemodifier", value);
-                        if (window.content.document.title.length > 0)
-                            document.title = window.content.document.title + " - " + value;
-                        else
-                            document.title = value;
-                    }
-                    catch (e)
-                    {
-                        liberator.log("Couldn't set titlestring", 3);
-                    }
-                }
-            });
-
         liberator.options.add(["verbose", "vbs"],
             "Define which type of messages are logged",
             "number", 0,
@@ -892,7 +870,6 @@ const liberator = (function () //{{{
             loadModule("autocommands", liberator.AutoCommands);
             loadModule("io",           liberator.IO);
             loadModule("completion",   liberator.Completion);
-            // loadModule("previewwindow" = liberator.InformationList("liberator-previewwindow", { incrementalFill: false, maxItems: 10 });
 
             // This adds options/mappings/commands which are only valid in this particular extension
             if (liberator.config.init)
diff --git a/content/muttator.js b/content/muttator.js
index 93dc03f7..2c68b4b6 100644
--- a/content/muttator.js
+++ b/content/muttator.js
@@ -106,6 +106,8 @@ liberator.config = {
         // load Muttator specific modules
         if (this.isComposeWindow)
         {
+            this.features = ["mail"];
+
             // TODO: move mappings elsewhere, probably compose.js
             liberator.mappings.add([liberator.modes.COMPOSE],
                 ["e"], "Edit message",
diff --git a/content/vimperator.js b/content/vimperator.js
index b637840a..f58b6e8e 100644
--- a/content/vimperator.js
+++ b/content/vimperator.js
@@ -376,6 +376,28 @@ liberator.config = { //{{{
                 }
             });
 
+        liberator.options.add(["titlestring"],
+            "Change the title of the window",
+            "string", "Vimperator",
+            {
+                setter: function (value)
+                {
+                    try
+                    {
+                        var id = liberator.config.mainWindowID || "main-window";
+                        document.getElementById(id).setAttribute("titlemodifier", value);
+                        if (window.content.document.title.length > 0)
+                            document.title = window.content.document.title + " - " + value;
+                        else
+                            document.title = value;
+                    }
+                    catch (e)
+                    {
+                        liberator.log("Couldn't set titlestring", 3);
+                    }
+                }
+            });
+
         liberator.options.add(["urlseparator"],
             "Set the separator regexp used to separate multiple URL args",
             "string", ",\\s");