Slick (mootools) selector engine documentation - mootools

Question

Mootools slick selector engine documentation seems kind of sparse / unfriendly.
http://mootools.net/docs/core/Slick/Slick
An example:
Normally i can reach the last child of an element with:
$('wrapper').getLast().setStyle('background-color','green');
how do i utilize the new slick engine to achieve the same?
And where is the documentation?
Should i just learn CSS3 selectors?
In their example they use $$('p.foo !^') to get the last child of p class foo whatever that means. (do they mean the last instance of p.foo in the $$ array or the last child of the last element???)
Here i tried to fiddle a bit, the last two doesn't work:
http://jsfiddle.net/XLVr6/1/

Answer 1

The example bellow will select the last child of the element with id="wrapper. It will only return one element.
$$('#wrapper !^').setStyle('background-color','red');
or better way as only one element is needed, as it is faster:
document.getElement('#wrapper !^').setStyle('background-color','red');
However, if it's written like this where we select the last child of all p-elements on the page with class="wrapper"
$$('p.wrapper !^').setStyle('background-color','red');
Another way to do it is like this, however next example is faster:
('someId').getLast().setStyle('background-color','red');
As pointed out by Dimitar this is a better (faster) way to do it:
document.getElement('#someId :last-child')
As for your fiddle, the two last selectors should be written like this:
$$('#wrapper :last-child').setStyle('background-color','red');
$$('#wrapper !^').setStyle('background-color','red');
Please note the space between "wrapper" and ":last-child", that is because we are selecting the last child of a the child elements of "wrapper".