diff --git a/src/basic/Rectangle.js b/src/basic/Rectangle.js
index 09a388aa..bd104ee6 100644
--- a/src/basic/Rectangle.js
+++ b/src/basic/Rectangle.js
@@ -98,11 +98,13 @@ var Rectangle = Base.extend(/** @lends Rectangle# */{
                         arg0.width || 0, arg0.height || 0);
                 read = 1;
             } else if (arg0.from === undefined && arg0.to === undefined) {
-                // Use Base.filter() to support whatever property the rectangle
-                // can take, but handle from/to separately below.
+                // Use `Base.readSupported()` to read and consume whatever
+                // property the rectangle can receive, but handle `from` / `to`
+                // separately below.
                 this._set(0, 0, 0, 0);
-                Base.filter(this, arg0);
-                read = 1;
+                if (Base.readSupported(arguments, this)) {
+                    read = 1;
+                }
             }
         }
         if (read === undefined) {
@@ -141,13 +143,13 @@ var Rectangle = Base.extend(/** @lends Rectangle# */{
             }
             this._set(x, y, width, height);
             read = arguments.__index;
-            // arguments.__filtered wouldn't survive the function call even if a
-            // previous arguments list was passed through Function#apply().
-            // Return it on the object instead, see Base.read()
-            var filtered = arguments.__filtered;
-            if (filtered)
-                this.__filtered = filtered;
         }
+        // arguments.__filtered wouldn't survive the function call even if a
+        // previous arguments list was passed through Function#apply().
+        // Return it on the object instead, see Base.read()
+        var filtered = arguments.__filtered;
+        if (filtered)
+            this.__filtered = filtered;
         if (this.__read)
             this.__read = read;
         return this;
diff --git a/src/core/Base.js b/src/core/Base.js
index 52d963af..dcb668ef 100644
--- a/src/core/Base.js
+++ b/src/core/Base.js
@@ -269,11 +269,11 @@ statics: /** @lends Base */{
     },
 
     /**
-     * Allows using of Base.read() mechanism in combination with reading named
-     * arguments form a passed property object literal. Calling Base.readNamed()
-     * can read both from such named properties and normal unnamed arguments
-     * through Base.read(). In use for example for the various
-     * Path.Constructors.
+     * Allows using of `Base.read()` mechanism in combination with reading named
+     * arguments form a passed property object literal. Calling
+     * `Base.readNamed()` can read both from such named properties and normal
+     * unnamed arguments through `Base.read()`. In use for example for
+     * the various `Path` constructors in `Path.Constructors.js`.
      *
      * @param {Array} list the list to read from, either an arguments object or
      *     a normal array
@@ -287,24 +287,68 @@ statics: /** @lends Base */{
      */
     readNamed: function(list, name, start, options, amount) {
         var value = this.getNamed(list, name),
-            hasObject = value !== undefined;
-        if (hasObject) {
-            // Create a _filtered object that inherits from list[0], and
+            hasValue = value !== undefined;
+        if (hasValue) {
+            // Create a _filtered object that inherits from `source`, and
             // override all fields that were already read with undefined.
             var filtered = list.__filtered;
             if (!filtered) {
-                filtered = list.__filtered = Base.create(list[0]);
-                // Point _unfiltered to the original so Base#_set() can
-                // execute hasOwnProperty on it.
-                filtered.__unfiltered = list[0];
+                var source = this.getSource(list);
+                filtered = list.__filtered = Base.create(source);
+                // Point __unfiltered to the original, so `Base.filter()` can
+                // use it to get all keys to iterate over.
+                filtered.__unfiltered = source;
             }
             // delete wouldn't work since the masked parent's value would
             // shine through.
             filtered[name] = undefined;
         }
-        var l = hasObject ? [value] : list,
-            res = this.read(l, start, options, amount);
-        return res;
+        return this.read(hasValue ? [value] : list, start, options, amount);
+    },
+
+    /**
+     * If `list[0]` is a source object, calls `Base.readNamed()` for each key in
+     * it that is supported on `dest`, consuming these values.
+     *
+     * @param {Array} list the list to read from, either an arguments object or
+     *     a normal array
+     * @param {Object} dest the object on which to set the supported properties
+     * @return {Boolean} {@true if any property was read from the source object}
+     */
+    readSupported: function(list, dest) {
+        var source = this.getSource(list),
+            that = this,
+            read = false;
+        if (source) {
+            // If `source` is a filtered object, we get the keys from the the
+            // original object (it's parent / prototype). See _filtered
+            // inheritance trick in the argument reading code.
+            Object.keys(source).forEach(function(key) {
+                if (key in dest) {
+                    var value = that.readNamed(list, key);
+                    // Due to the _filtered inheritance trick, undefined is used
+                    // to mask already consumed named arguments.
+                    if (value !== undefined) {
+                        dest[key] = value;
+                    }
+                    read = true;
+                }
+            });
+        }
+        return read;
+    },
+
+    /**
+     * @return the arguments object if the list provides one at `list[0]`
+     */
+    getSource: function(list) {
+        var source = list.__source;
+        if (source === undefined) {
+            var arg = list.length === 1 && list[0];
+            source = list.__source = arg && Base.isPlainObject(arg)
+                ? arg : null;
+        }
+        return source;
     },
 
     /**
@@ -314,12 +358,11 @@ statics: /** @lends Base */{
      *     provided, it returns the whole arguments object
      */
     getNamed: function(list, name) {
-        var arg = list[0];
-        if (list._hasObject === undefined)
-            list._hasObject = list.length === 1 && Base.isPlainObject(arg);
-        if (list._hasObject)
+        var source = this.getSource(list);
+        if (source) {
             // Return the whole arguments object if no name is provided.
-            return name ? arg[name] : list.__filtered || arg;
+            return name ? source[name] : list.__filtered || source;
+        }
     },
 
     /**
diff --git a/src/item/Shape.js b/src/item/Shape.js
index 63bf40e2..e9b7e340 100644
--- a/src/item/Shape.js
+++ b/src/item/Shape.js
@@ -82,7 +82,7 @@ var Shape = Item.extend(/** @lends Shape# */{
     setSize: function(/* size */) {
         var size = Size.read(arguments);
         if (!this._size) {
-            // First time, e.g. whean reading from JSON...
+            // First time, e.g. when reading from JSON...
             this._size = size.clone();
         } else if (!this._size.equals(size)) {
             var type = this._type,
@@ -101,8 +101,8 @@ var Shape = Item.extend(/** @lends Shape# */{
                 this._radius._set(width / 2, height / 2);
             }
             this._size._set(width, height);
+            this._changed(/*#=*/Change.GEOMETRY);
         }
-        this._changed(/*#=*/Change.GEOMETRY);
     },
 
     /**
@@ -130,7 +130,7 @@ var Shape = Item.extend(/** @lends Shape# */{
         } else {
             radius = Size.read(arguments);
             if (!this._radius) {
-                // First time, e.g. whean reading from JSON...
+                // First time, e.g. when reading from JSON...
                 this._radius = radius.clone();
             } else {
                 if (this._radius.equals(radius))
@@ -390,10 +390,13 @@ new function() { // Scope for _contains() and _hitTestSelf() code.
 // Mess with indentation in order to get more line-space below:
 statics: new function() {
     function createShape(type, point, size, radius, args) {
-        var item = new Shape(Base.getNamed(args), point);
+        // Use `Base.create()` to avoid calling `initialize()` until after the
+        // internal fields are set here, then call `_initialize()` directly:
+        var item = Base.create(Shape.prototype);
         item._type = type;
         item._size = size;
         item._radius = radius;
+        item._initialize(Base.getNamed(args), point);
         return item;
     }