extend() doesn't go through the properties recursively.

For the following case:

var a = {prop1: {prop1a: "1a", prop2a: "5a"}};
var b = {prop1: {prop1a: "1b"}};
$.extend(a, b);

you would expect the result:

a = {prop1: {prop1a: "1b", prop2a: "5a"}

but the result currently is:

a = {prop1: {prop1a: "1b"}

It copies (overwrites) the property "prop1" from "b" wihthout keeping "prop2a" from "a".

This code snipped fixes the bug (just replace the while loop in "jQuery.extend" with this code)

	while (prop = arguments[a++])
		// Extend the base object
		for ( var i in prop )
                {
                    // prevent endless inheritances/loops
                    if (target == prop[i])
                        continue;

                    // extend recursively if current prop is an object, and
                    // target has props of the same name
                    if (typeof prop[i] == 'object' && target[i])
                        jQuery.extend(target[i],prop[i]);
                    else
                        target[i] = prop[i];
                }