diff --git a/source/Ox.UI/js/Form/OptionGroup.js b/source/Ox.UI/js/Form/OptionGroup.js
index c0065356..fe5614a3 100644
--- a/source/Ox.UI/js/Form/OptionGroup.js
+++ b/source/Ox.UI/js/Form/OptionGroup.js
@@ -10,6 +10,8 @@ Ox.OptionGroup <f> OptionGroup
     property <s|'checked'> property to check
 @*/
 
+// FIXME: Should be moved to Ox.js
+
 Ox.OptionGroup = function(items, min, max, property) {
 
     var length = items.length;
diff --git a/source/Ox/js/Array.js b/source/Ox/js/Array.js
index f65a7e28..fc18b42b 100644
--- a/source/Ox/js/Array.js
+++ b/source/Ox/js/Array.js
@@ -457,6 +457,33 @@ Ox.indexOf = function(arr) {
 };
 */
 
+/*@
+Ox.last <f> Gets or sets the last element of an array
+    Unlike `arrayWithALongName[arrayWithALongName.length - 1]`,
+    `Ox.last(arrayWithALongName)` is short.
+    <script>
+        Ox.test.array = [1, 2, 3];
+    </script>
+    > Ox.last(Ox.test.array)
+    3
+    > Ox.last(Ox.test.array, 4)
+    [1, 2, 4]
+    > Ox.test.array
+    [1, 2, 4]
+    > Ox.last('123')
+    '3'
+@*/
+Ox.last = function(array, value) {
+    var ret;
+    if (arguments.length == 1) {
+        ret = array[array.length - 1];
+    } else {
+        array[array.length - 1] = value;
+        ret = array;
+    }
+    return ret;
+};
+
 /*@
 Ox.makeArray <f> Wraps any non-array in an array.
     (value) -> <a> Array
diff --git a/source/Ox/js/Async.js b/source/Ox/js/Async.js
index a16e92b4..badbb702 100644
--- a/source/Ox/js/Async.js
+++ b/source/Ox/js/Async.js
@@ -31,8 +31,16 @@
     };
 
     /*@
-    Ox.nonblockingForEach <f> Non-blocking forEach with synchronous iterator
+    Ox.nonblockingForEach <f> Non-blocking `forEach` with synchronous iterator
         (col, iterator[, that], callback[, ms]) -> <u> undefined
+        collection <a|o|s> Collection
+        iterator <f> Iterator function
+            value <*> Value
+            key <n|s> Key
+            collection <a|o|s> The collection
+        that <o> The iterator's `this` binding
+        callback <f> Callback function
+        ms <n> Number of milliseconds after which to insert a `setTimeout` call
     @*/
     Ox.nonblockingForEach = function(collection, iterator, that, callback, ms) {
         var i = 0, keys, last = Ox.last(arguments),
@@ -76,12 +84,13 @@
     };
 
     /*@
-    Ox.nonblockingMap <f> Non-blocking map with synchronous iterator
-        (collection, iterator[, that]) -> <u> undefined
+    Ox.nonblockingMap <f> Non-blocking `map` with synchronous iterator
+        (collection, iterator[, that], callback[, ms]) -> <u> undefined
         collection <a|o|s> Collection
         iterator <f> Iterator function
-        that <o> The iterator's this binding
+        that <o> The iterator's `this` binding
         callback <f> Callback function
+        ms <n> Number of milliseconds after which to insert a `setTimeout` call
         <script>
             var time = +new Date();
             Ox.nonblockingMap(
@@ -114,7 +123,7 @@
     };
 
     /*@
-    Ox.parallelForEach <f> forEach with asynchronous iterator, running in parallel
+    Ox.parallelForEach <f> `forEach` with asynchronous iterator, running in parallel
         (collection, iterator[, that], callback) -> <u> undefined
         collection <a|o|s> Collection
         iterator <f> Iterator function
@@ -140,7 +149,7 @@
     };
 
     /*@
-    Ox.parallelMap <f> Parallel map with asynchronous iterator
+    Ox.parallelMap <f> Parallel `map` with asynchronous iterator
         (collection, iterator[, that], callback) -> <u> undefined
         collection <a|o|s> Collection
         iterator <f> Iterator function
@@ -173,7 +182,7 @@
     };
 
     /*@
-    Ox.serialForEach <f> forEach with asynchronous iterator, run serially
+    Ox.serialForEach <f> `forEach` with asynchronous iterator, run serially
         (collection, iterator[, that], callback) -> <u> undefined
         collection <a|o|s> Collection
         iterator <f> Iterator function
@@ -208,7 +217,7 @@
     };
 
     /*@
-    Ox.serialMap <f> Serial map with asynchronous iterator
+    Ox.serialMap <f> Serial `map` with asynchronous iterator
         (collection, iterator[, that], callback) -> <u> undefined
         collection <a|o|s> Collection
         iterator <f> Iterator function
diff --git a/source/Ox/js/Collection.js b/source/Ox/js/Collection.js
index ee57eb0a..03ec6c59 100644
--- a/source/Ox/js/Collection.js
+++ b/source/Ox/js/Collection.js
@@ -16,13 +16,17 @@ Ox.avg = function(collection) {
 };
 
 /*@
-Ox.clone <f> Returns a (shallow or deep) copy of an object or array
+Ox.clone <f> Returns a (shallow or deep) copy of an array or object
     > (function() { var a = ['v'], b = Ox.clone(a); a[0] = null; return b[0]; }())
     'v'
     > (function() { var a = {k: 'v'}, b = Ox.clone(a); a.k = null; return b.k; }())
     'v'
     > Ox.clone(0)
     0
+    > (function() { var a = [[0, 1]], b = Ox.clone(a); a[0][0] = null; return b[0]; }())
+    [null, 1]
+    > (function() { var a = [[0, 1]], b = Ox.clone(a, true); a[0][0] = null; return b[0]; }())
+    [0, 1]
 @*/
 Ox.clone = Ox.copy = function(collection, deep) {
     // fixme: copy or clone?
@@ -44,13 +48,16 @@ Ox.clone = Ox.copy = function(collection, deep) {
 
 /*@
 Ox.contains <f> Tests if a collection contains a value
+    (collection, value) -> <b> If true, the collection contains the value
+    collection <a|o|s> Collection
+    value <*> Any value
     > Ox.contains(['foo', 'bar'], 'foo')
     true
     > Ox.contains({foo: 'bar'}, 'bar')
     true
     > Ox.contains({foo: 'bar'}, 'foo')
     false
-    > Ox.contains("foobar", "bar")
+    > Ox.contains('foobar', 'bar')
     true
 @*/ 
 // FIXME: a shorter name would be nice (but IE8 doesn't like 'in')
@@ -62,6 +69,10 @@ Ox.contains = function(collection, value) {
 
 /*@
 Ox.count <f> Counts the occurences of values in a collection
+    (collection) -> <o> Number of occurrences per value
+    (collection, value) -> <n> Number of occurrences of the given value
+    collection <a|o|s> Collection
+    value <*> Any value
     > Ox.count(['f', 'o', 'o'])
     {f: 1, o: 2}
     > Ox.count({a: 'f', b: 'o', c: 'o'})
@@ -83,7 +94,14 @@ Ox.count = function(collection, value) {
 
 /*@
 Ox.every <f> Tests if every element of a collection satisfies a given condition
-    Unlike `[].every()`, `Ox.every()` works for arrays, objects and strings.
+    Unlike `Array.prototype.every`, `Ox.every` works for arrays, objects and
+    strings.
+    (collection, iterator) -> <b> True if every element passes the test
+    collection <a|o|s> Collection
+    iterator <f> Iterator
+        value <*> Value
+        key <n|s> Index or key
+        collection <a|o|s> The collection
     > Ox.every([0, 1, 2], function(v, i) { return v == i; })
     true
     > Ox.every({a: 1, b: 2, c: 3}, function(v) { return v == 1; })
@@ -101,7 +119,8 @@ Ox.every = function(collection, iterator) {
 
 /*@
 Ox.filter <f> Filters a collection by a given condition
-    Unlike `[].filter()`, `Ox.filter()` works for arrays, objects and strings.
+    Unlike `Array.prototype.filter`, `Ox.filter` works for arrays, objects and
+    strings.
     > Ox.filter([2, 1, 0], function(v, i) { return v == i; })
     [1]
     > Ox.filter({a: 'c', b: 'b', c: 'a'}, function(v, k) { return v == k; })
@@ -128,31 +147,32 @@ Ox.filter = function(collection, iterator, that) {
     return ret;
 };
 
-// FIXME: documentation is outdated!
 /*@
 Ox.forEach <f> forEach loop
-    `Ox.forEach()` loops over arrays, objects and strings. Returning `false`
-    from the iterator function acts like a `break` statement (unlike
-    `[].forEach()`, like `$.each()`). The arguments of the iterator function are
-    `(value, key, index)` (more like `[].forEach()` than like `$.each()`).
-    (collection, callback) <a|o|s> The collection
-    (collection, callback, includePrototype) <a|o|s> The collection
-    collection <a|o|s> An array, object or string
-    callback <f> Iterator function
+    `Ox.forEach` loops over arrays, objects and strings. Calling `Ox.Break`
+    inside the iterator or returning `false` from the iterator acts like a
+    `break` statement. Unlike `Array.prototype.forEach`, which leaks its counter
+    variable to the outer scope, `Ox.forEach` returns it.
+    (collection, iterator[, that]) -> <n> Next index
+    collection <a|o|s> Collection
+    iterator <f> Iterator
         value <*> Value
-        key <n|s> Key
-    includePrototype <b|false> If true, include prototype properties
+        key <n|s> Index or key
+        collection <a|o|s> The collection
+    that <o> The iterator's `this` binding
     <script>
         Ox.test.string = "";
-        Ox.forEach(["f", "o", "o"], function(v, i) { Ox.test.string += i; });
-        Ox.forEach({a: "f", b: "o", c: "o"}, function(v, k) { Ox.test.string += k; });
+        Ox.forEach(['f', 'o', 'o'], function(v, i) { Ox.test.string += i; });
+        Ox.forEach({a: 'f', b: 'o', c: 'o'}, function(v, k) { Ox.test.string += k; });
         Ox.forEach("foo", function(v) { Ox.test.string += v; });
     </script>
     > Ox.test.string
     "012abcfoo"
+    > Ox.forEach({a: 'f', b: 'o', c: 'o'}, function(v, k) { return v != 'o' });
+    1
 @*/
 Ox.forEach = function(collection, iterator, that) {
-    var i, key, type = Ox.typeOf(collection);
+    var i = 0, key, type = Ox.typeOf(collection);
     if (type != 'array' && type != 'object') {
         collection = Ox.toArray(collection);
     }
@@ -166,6 +186,7 @@ Ox.forEach = function(collection, iterator, that) {
                         break;
                     }
                 }
+                i++;
             }
         } else {
             for (i = 0; i < collection.length; i++) {
@@ -183,7 +204,7 @@ Ox.forEach = function(collection, iterator, that) {
             throw error;
         }
     }
-    return type == 'object' ? key : i;
+    return i;
 };
 
 /*@
@@ -201,7 +222,8 @@ Ox.indexOf = function(collection, test) {
     var index = Ox.forEach(collection, function(value) {
         test(value) && Ox.Break();
     });
-    return index == collection.length ? -1 : index;
+    return Ox.isObject(collection) ? Object.keys(collection)[index] || null
+        : index == collection.length ? -1 : index;
 };
 
 /*@
@@ -248,33 +270,6 @@ Ox.isEmpty = function(value) {
     return Ox.len(value) === 0;
 };
 
-/*@
-Ox.last <f> Gets or sets the last element of an array
-    Unlike `arrayWithALongName[arrayWithALongName.length - 1]`,
-    `Ox.last(arrayWithALongName)` is short.
-    <script>
-        Ox.test.array = [1, 2, 3];
-    </script>
-    > Ox.last(Ox.test.array)
-    3
-    > Ox.last(Ox.test.array, 4)
-    [1, 2, 4]
-    > Ox.test.array
-    [1, 2, 4]
-    > Ox.last('123')
-    '3'
-@*/
-Ox.last = function(array, value) {
-    var ret;
-    if (arguments.length == 1) {
-        ret = array[array.length - 1];
-    } else {
-        array[array.length - 1] = value;
-        ret = array;
-    }
-    return ret;
-};
-
 /*@
 Ox.len <f> Returns the length of an array, node list, object or string
     Not to be confused with `Ox.length`, which is the `length` property of the
@@ -310,7 +305,8 @@ Ox.len = function(collection) {
 
 /*@
 Ox.map <f> Transforms the values of an array, object or string
-    Unlike `[].map()`, `Ox.map()` works for arrays, objects and strings.
+    Unlike `Array.prototype.map`, `Ox.map` works for arrays, objects and
+    strings.
     > Ox.map([2, 1, 0], function(v, i) { return v == i; })
     [false, true, false]
     > Ox.map({a: 'b', b: 'b', c: 'b'}, function(v, k) { return v == k; })
@@ -391,36 +387,6 @@ Ox.reverse = function(collection) {
         : collection.toString().split('').reverse().join('');
 };
 
-/*@
-Ox.setPropertyOnce <f> Sets a property once
-    Given a array of objects, each of which has a property with a boolean
-    value, this sets exactly one of these to true, and returns the index
-    of the object whose property is true.
-    > Ox.setPropertyOnce([{selected: false}, {selected: false}], 'selected')
-    0
-    > Ox.setPropertyOnce([{selected: false}, {selected: true}], 'selected')
-    1
-    > Ox.setPropertyOnce([{selected: true}, {selected: true}], 'selected')
-    0    
-@*/
-// fixme: strange name, and shouldn't it return the full array?
-// fixme: unused, there is OptionGroup (which should be part of Ox.js)
-Ox.setPropertyOnce = function(arr, str) {
-    var pos = -1;
-    Ox.forEach(arr, function(v, i) {
-        if (pos == -1 && arr[i][str]) {
-            pos = i;
-        } else if (pos > -1 && arr[i][str]) {
-            delete arr[i][str];
-        }
-    });
-    if (pos == -1) {
-        arr[0][str] = true;
-        pos = 0;
-    }
-    return pos;
-};
-
 /*@
 Ox.shuffle <f> Randomizes the order of values within a collection
     > Ox.shuffle([1, 2, 3]).length
@@ -484,7 +450,8 @@ if (
 
 /*@
 Ox.some <f> Tests if one or more elements of a collection meet a given condition
-    Unlike `[].some()`, `Ox.some()` works for arrays, objects and strings.
+    Unlike `Array.prototype.some`, `Ox.some` works for arrays, objects and
+    strings.
     > Ox.some([2, 1, 0], function(i, v) { return i == v; })
     true
     > Ox.some({a: 1, b: 2, c: 3}, function(v) { return v == 1; })
@@ -545,6 +512,8 @@ Ox.objectToArray = function(object, key) {
 
 /*@
 Ox.values <f> Returns the values of a collection
+    (collection) -> <a> Array of values
+    collection <a|o|s> Collection
     > Ox.values([1, 2, 3])
     [1, 2, 3]
     > Ox.values({a: 1, b: 2, c: 3})
@@ -571,6 +540,13 @@ Ox.values = function(collection) {
 
 /*@
 Ox.walk <f> Iterates over a nested data structure
+    (collection, iterator[, that]) -> <u> undefined
+    collection <a|o|s> Collection
+    iterator <f> Iterator
+        value <*> Value
+        keys <a> Array of keys
+        collection <a|o|s> The collection
+    that <o> The iterator's `this` binding
     <script>
         Ox.test.number = 0;
         Ox.walk({a: 1, b: {c: 2, d: 3}}, function(value) {
@@ -586,11 +562,11 @@ Ox.walk <f> Iterates over a nested data structure
     > Ox.test.array
     [['a'], ['b', 'c'], ['b', 'd']]
 @*/
-Ox.walk = function(collection, iterator, keys) {
+Ox.walk = function(collection, iterator, that, keys) {
     keys = keys || [];
     Ox.forEach(collection, function(value, key) {
         var keys_ = keys.concat(key);
-        iterator(value, keys_, collection);
-        Ox.walk(collection[key], iterator, keys_);
+        iterator.call(that, value, keys_, collection);
+        Ox.walk(collection[key], iterator, that, keys_);
     });
 };