Fix some minor bugs.

--HG--
branch : groups

common/content/contexts.js

@@ -17,6 +17,10 @@ var Group = Class("Group", {
     cleanup: function cleanup() {
         for (let hive in values(this.hives))
             dactyl.trapErrors("cleanup", hive);
+
+        this.hives = [];
+        for (let hive in keys(Group.hiveMap))
+            delete this[hive];
     },
     destroy: function destroy() {
         for (let hive in values(this.hives))
@@ -29,8 +33,6 @@ var Group = Class("Group", {
 
     get builtin() contexts.builtinGroups.indexOf(this) >= 0,
 
-    hives: {}
-
 }, {
     compileFilter: function (patterns) {
 
@@ -165,17 +167,22 @@ var Contexts = Module("contexts", {
         if (group)
             name = group.name;
 
-        if (replace)
+        if (!group) {
-            this.removeGroup(name);
-
-        if (!group || replace) {
-            dactyl.assert(name !== "default", "Illegal group name");
-
             group = Group(name, description, filter, persist);
             this.groupList.unshift(group);
             this.groupMap[name] = group;
             this.hiveProto.__defineGetter__(name, function () group[this._hive]);
         }
+
+        if (replace) {
+            dactyl.trapErrors("cleanup", group);
+            if (description)
+                group.description = description;
+            if (filter)
+                group.filter = filter
+            group.persist = persist;
+        }
+
         delete this.groups;
         return group;
     },

common/modules/util.jsm

@@ -770,14 +770,18 @@ var Util = Module("Util", XPCOM([Ci.nsIObserver, Ci.nsISupportsWeakReference]),
         try {
             let xmlhttp = services.Xmlhttp();
             xmlhttp.mozBackgroundRequest = true;
-            if (params.callback) {
+
-                xmlhttp.onload = function handler(event) { util.trapErrors(params.callback, params, xmlhttp, event) };
+            let async = params.callback || params.onload || params.onerror;
-                xmlhttp.onerror = xmlhttp.onload;
+            if (async) {
+                xmlhttp.onload = function handler(event) { util.trapErrors(params.onload || params.callback, params, xmlhttp, event) };
+                xmlhttp.onerror = function handler(event) { util.trapErrors(params.onerror || params.callback, params, xmlhttp, event) };
             }
             if (params.mimeType)
                 xmlhttp.overrideMimeType(params.mimeType);
 
-            xmlhttp.open(params.method || "GET", url, !!params.callback, params.user, params.pass);
+            xmlhttp.open(params.method || "GET", url, async,
+                         params.user, params.pass);
+
             xmlhttp.send(null);
             return xmlhttp;
         }