diff --git a/common/content/autocommands.js b/common/content/autocommands.js
index a60b64a5..5ff436f2 100644
--- a/common/content/autocommands.js
+++ b/common/content/autocommands.js
@@ -245,7 +245,7 @@ var AutoCommands = Module("autocommands", {
         };
     },
     javascript: function () {
-        JavaScript.setCompleter(this.get, [function () Iterator(config.autocommands)]);
+        JavaScript.setCompleter(autocommands.get, [function () Iterator(config.autocommands)]);
     },
     options: function () {
         options.add(["eventignore", "ei"],
diff --git a/common/content/buffer.js b/common/content/buffer.js
index 62d5a69e..146daf9b 100644
--- a/common/content/buffer.js
+++ b/common/content/buffer.js
@@ -262,7 +262,7 @@ var Buffer = Module("buffer", {
         dactylLoadCount: 0,
 
         // XXX: function may later be needed to detect a canceled synchronous openURL()
-        onStateChange: function onStateChange(webProgress, request, flags, status) {
+        onStateChange: util.wrapCallback(function onStateChange(webProgress, request, flags, status) {
             onStateChange.superapply(this, arguments);
             // STATE_IS_DOCUMENT | STATE_IS_WINDOW is important, because we also
             // receive statechange events for loading images and other parts of the web page
@@ -286,9 +286,9 @@ var Buffer = Module("buffer", {
                     statusline.updateUrl();
                 }
             }
-        },
+        }),
         // for notifying the user about secure web pages
-        onSecurityChange: function onSecurityChange(webProgress, request, state) {
+        onSecurityChange: util.wrapCallback(function onSecurityChange(webProgress, request, state) {
             onSecurityChange.superapply(this, arguments);
             if (state & Ci.nsIWebProgressListener.STATE_IS_BROKEN)
                 statusline.security = "broken";
@@ -300,19 +300,19 @@ var Buffer = Module("buffer", {
                 statusline.security = "insecure";
             if (webProgress && webProgress.DOMWindow)
                 webProgress.DOMWindow.document.dactylSecurity = statusline.security;
-        },
-        onStatusChange: function onStatusChange(webProgress, request, status, message) {
+        }),
+        onStatusChange: util.wrapCallback(function onStatusChange(webProgress, request, status, message) {
             onStatusChange.superapply(this, arguments);
             statusline.updateUrl(message);
-        },
-        onProgressChange: function onProgressChange(webProgress, request, curSelfProgress, maxSelfProgress, curTotalProgress, maxTotalProgress) {
+        }),
+        onProgressChange: util.wrapCallback(function onProgressChange(webProgress, request, curSelfProgress, maxSelfProgress, curTotalProgress, maxTotalProgress) {
             onProgressChange.superapply(this, arguments);
-            if (webProgress.DOMWindow)
+            if (webProgress && webProgress.DOMWindow)
                 webProgress.DOMWindow.dactylProgress = curTotalProgress / maxTotalProgress;
             statusline.progress = curTotalProgress / maxTotalProgress;
-        },
+        }),
         // happens when the users switches tabs
-        onLocationChange: function onLocationChange(webProgress, request, uri) {
+        onLocationChange: util.wrapCallback(function onLocationChange(webProgress, request, uri) {
             onLocationChange.superapply(this, arguments);
 
             delete mappings.hives;
@@ -352,13 +352,13 @@ var Buffer = Module("buffer", {
                 if (loaded.commandline)
                     commandline.clear();
             }, 500);
-        },
+        }),
         // called at the very end of a page load
-        asyncUpdateUI: function asyncUpdateUI() {
+        asyncUpdateUI: util.wrapCallback(function asyncUpdateUI() {
             asyncUpdateUI.superapply(this, arguments);
             util.timeout(function () { statusline.updateUrl(); }, 100);
-        },
-        setOverLink: function setOverLink(link, b) {
+        }),
+        setOverLink: util.wrapCallback(function setOverLink(link, b) {
             setOverLink.superapply(this, arguments);
             switch (options["showstatuslinks"]) {
             case "status":
@@ -371,7 +371,7 @@ var Buffer = Module("buffer", {
                     commandline.clear();
                 break;
             }
-        },
+        }),
     },
 
     /**
diff --git a/common/content/commandline.js b/common/content/commandline.js
index 4dd50eee..9898d77a 100644
--- a/common/content/commandline.js
+++ b/common/content/commandline.js
@@ -352,8 +352,8 @@ var CommandMode = Class("CommandMode", {
             if (this.history)
                 this.history.save();
 
-            commandline.hideCompletions();
             this.resetCompletions();
+            commandline.hideCompletions();
 
             modes.delay(function () {
                 if (!this.keepCommand || commandline.silent || commandline.quiet)
@@ -504,11 +504,6 @@ var CommandLine = Module("commandline", {
                 }, message));
             }
         }; //}}}
-
-        this._silent = false;
-        this._quiet = false;
-        this._lastEcho = null;
-
     },
 
     /**
@@ -546,12 +541,14 @@ var CommandLine = Module("commandline", {
 
     get completionContext() this._completions.context,
 
+    _silent: false,
     get silent() this._silent,
     set silent(val) {
         this._silent = val;
         this.quiet = this.quiet;
     },
 
+    _quite: false,
     get quiet() this._quiet,
     set quiet(val) {
         this._quiet = val;
@@ -665,6 +662,8 @@ var CommandLine = Module("commandline", {
         }
     },
 
+    _lastEcho: null,
+
     /**
      * Output the given string onto the command line. With no flags, the
      * message will be shown in the status line if it's short enough to
diff --git a/common/content/dactyl.js b/common/content/dactyl.js
index 1defb6cf..90d88c87 100644
--- a/common/content/dactyl.js
+++ b/common/content/dactyl.js
@@ -12,7 +12,6 @@ default xml namespace = XHTML;
 XML.ignoreWhitespace = false;
 XML.prettyPrinting = false;
 
-var plugins = { __proto__: modules };
 var userContext = { __proto__: modules };
 var _userContext = newContext(userContext);
 
@@ -53,7 +52,6 @@ var Dactyl = Module("dactyl", XPCOM(Ci.nsISupportsWeakReference, ModuleBase), {
 
     destroy: function () {
         autocommands.trigger("LeavePre", {});
-        storage.saveAll();
         dactyl.triggerObserver("shutdown", null);
         util.dump("All dactyl modules destroyed\n");
         autocommands.trigger("Leave", {});
@@ -337,7 +335,7 @@ var Dactyl = Module("dactyl", XPCOM(Ci.nsISupportsWeakReference, ModuleBase), {
             dactyl.reportError(str);
         if (typeof str == "object" && "echoerr" in str)
             str = str.echoerr;
-        else if (isinstance(str, ["Error"]))
+        else if (isinstance(str, ["Error"]) && str.fileName)
             str = <>{str.fileName.replace(/^.* -> /, "")}: {str.lineNumber}: {str}</>;
 
         if (options["errorbells"])
diff --git a/common/content/mappings.js b/common/content/mappings.js
index dd19bda4..a69a64eb 100644
--- a/common/content/mappings.js
+++ b/common/content/mappings.js
@@ -862,7 +862,7 @@ var Mappings = Module("mappings", {
         };
     },
     javascript: function () {
-        JavaScript.setCompleter(this.get,
+        JavaScript.setCompleter(mappings.get,
             [
                 null,
                 function (context, obj, args) {
diff --git a/common/content/mow.js b/common/content/mow.js
index 1cea5fb5..8a130fbb 100644
--- a/common/content/mow.js
+++ b/common/content/mow.js
@@ -4,6 +4,7 @@
 //
 // This work is licensed for reuse under an MIT license. Details are
 // given in the LICENSE.txt file included with this file.
+"use strict";
 
 var MOW = Module("mow", {
     init: function () {
@@ -71,7 +72,6 @@ var MOW = Module("mow", {
         if (!commandline.commandVisible)
             commandline.hide();
 
-        this._startHints = false;
         if (modes.main != modes.OUTPUT_MULTILINE) {
             modes.push(modes.OUTPUT_MULTILINE, null, {
                 onKeyPress: this.closure.onKeyPress,
@@ -170,6 +170,7 @@ var MOW = Module("mow", {
             event.preventDefault();
         }
     },
+
     contextEvents: {
         popupshowing: function (event) {
             let menu = commandline.widgets.contextMenu;
@@ -261,8 +262,7 @@ var MOW = Module("mow", {
             if (!value && elem && elem.contentWindow == document.commandDispatcher.focusedWindow)
                 document.commandDispatcher.focusedWindow = content;
         }
-    }),
-
+    })
 }, {
 }, {
     mappings: function () {
@@ -277,7 +277,7 @@ var MOW = Module("mow", {
                 mow.echo(mow.lastOutput, "Normal");
             });
 
-        bind = function bind(keys, description, action, test, default_) {
+        let bind = function bind(keys, description, action, test, default_) {
             mappings.add([modes.OUTPUT_MULTILINE],
                 keys, description,
                 function (command) {
diff --git a/common/content/options.js b/common/content/options.js
index de3a713c..5ac9218e 100644
--- a/common/content/options.js
+++ b/common/content/options.js
@@ -1295,7 +1295,7 @@ var Options = Module("options", {
         };
     },
     javascript: function () {
-        JavaScript.setCompleter(this.get, [function () ([o.name, o.description] for (o in options))]);
+        JavaScript.setCompleter(options.get, [function () ([o.name, o.description] for (o in options))]);
     },
     sanitizer: function () {
         sanitizer.addItem("options", {
diff --git a/common/modules/addons.jsm b/common/modules/addons.jsm
index 9e0d04fb..3824f149 100644
--- a/common/modules/addons.jsm
+++ b/common/modules/addons.jsm
@@ -35,12 +35,12 @@ var AddonListener = Class("AddonListener", {
     onExternalInstall:   function (addon, existingAddon, needsRestart) {},
     onDownloadStarted:   listener("download", "started"),
     onDownloadEnded:     listener("download", "complete"),
-    onDownloadCancelled: listener("download", "cancelled"),
+    onDownloadCancelled: listener("download", "canceled"),
     onDownloadFailed:    listener("download", "failed"),
     onDownloadProgress:  function (install) {},
     onInstallStarted:    function (install) {},
     onInstallEnded:      listener("installation", "complete"),
-    onInstallCancelled:  listener("installation", "cancelled"),
+    onInstallCancelled:  listener("installation", "canceled"),
     onInstallFailed:     listener("installation", "failed")
 });
 
diff --git a/common/modules/base.jsm b/common/modules/base.jsm
index c3da6d2c..f147ebf1 100644
--- a/common/modules/base.jsm
+++ b/common/modules/base.jsm
@@ -616,12 +616,12 @@ function update(target) {
             if (desc.value instanceof Class.Property)
                 desc = desc.value.init(k) || desc.value;
             if (typeof desc.value == "function" && Object.getPrototypeOf(target)) {
-                let func = desc.value;
-                desc.value.__defineGetter__("super", function () Object.getPrototypeOf(target)[k]);
-                desc.value.superapply = function superapply(self, args)
+                let func = desc.value.wrapped || desc.value;
+                func.__defineGetter__("super", function () Object.getPrototypeOf(target)[k]);
+                func.superapply = function superapply(self, args)
                     let (meth = Object.getPrototypeOf(target)[k])
                         meth && meth.apply(self, args);
-                desc.value.supercall = function supercall(self)
+                func.supercall = function supercall(self)
                     func.superapply(self, Array.slice(arguments, 1));
             }
             Object.defineProperty(target, k, desc);
@@ -663,7 +663,7 @@ function Class() {
         superclass = args.shift();
 
     var Constructor = eval(String.replace(<![CDATA[
-        (function constructor() {
+        (function constructor(PARAMS) {
             var self = Object.create(Constructor.prototype, {
                 constructor: { value: Constructor },
             });
@@ -671,7 +671,9 @@ function Class() {
             var res = self.init.apply(self, arguments);
             return res !== undefined ? res : self;
         })]]>,
-        "constructor", (name || superclass.className).replace(/\W/g, "_")));
+        "constructor", (name || superclass.className).replace(/\W/g, "_"))
+            .replace("PARAMS", /^function .*?\((.*?)\)/.exec(args[0] && args[0].init || Class.prototype.init)[1]));
+
     Constructor.className = name || superclass.className || superclass.name;
 
     if ("init" in superclass.prototype)
diff --git a/common/modules/overlay.jsm b/common/modules/overlay.jsm
index 7b73be7c..411d7f43 100644
--- a/common/modules/overlay.jsm
+++ b/common/modules/overlay.jsm
@@ -144,6 +144,7 @@ var Overlay = Module("Overlay", {
                         return sandbox;
                     }
                 });
+                modules.plugins = create(modules);
                 modules.modules = modules;
                 window.dactyl = { modules: modules };
 
diff --git a/common/modules/storage.jsm b/common/modules/storage.jsm
index b41e86cf..64a7d7f2 100644
--- a/common/modules/storage.jsm
+++ b/common/modules/storage.jsm
@@ -152,6 +152,8 @@ var Storage = Module("Storage", {
     },
 
     cleanup: function () {
+        this.saveAll();
+
         for (let key in keys(this.keys)) {
             if (this[key].timer)
                 this[key].timer.flush();
diff --git a/common/modules/util.jsm b/common/modules/util.jsm
index 6b423c66..9bf6e2ee 100644
--- a/common/modules/util.jsm
+++ b/common/modules/util.jsm
@@ -32,8 +32,8 @@ memoize(this, "Commands", function () {
 var FailedAssertion = Class("FailedAssertion", ErrorBase);
 var Point = Struct("x", "y");
 
-var wrapCallback = function wrapCallback(fn)
-    fn.wrapper = (function wrappedCallback () {
+var wrapCallback = function wrapCallback(fn) {
+    fn.wrapper = function wrappedCallback () {
         try {
             return fn.apply(this, arguments);
         }
@@ -41,7 +41,10 @@ var wrapCallback = function wrapCallback(fn)
             util.reportError(e);
             return undefined;
         }
-    })
+    };
+    fn.wrapper.wrapped = fn;
+    return fn.wrapper;
+}
 
 var getAttr = function getAttr(elem, ns, name)
     elem.hasAttributeNS(ns, name) ? elem.getAttributeNS(ns, name) : null;
@@ -1585,6 +1588,8 @@ var Util = Module("Util", XPCOM([Ci.nsIObserver, Ci.nsISupportsWeakReference]),
             })();
         },
 
+    wrapCallback: wrapCallback,
+
     /**
      * Traps errors in the called function, possibly reporting them.
      *