is extending DOMElements pointless?

Dear developers,


can it be that implementing derived DOMElements is completely useless?

You can't write to them if they are created via 'new myDOMElement', and 
you can't get a version of your own class via 
'myDOMDocument->createElement()'...

I want to have different myDOMElements representing objects in a tree, 
which benefit from the native DOM functionality and add methods like 
'myDOMElement->loadChildrenFromDB()'. Currently, i am forced to use a 
somehow crappy implementation where myDOMElements are not derived and 
store the real DOMElement as a member, which has numerous drawbacks. :-|

So here are my questions:
- Is there a way to make myDOMElement writable?
- can you (kind of) typecast a native DOMElement to a myDOMElement with 
tricks?
- am i missing something?
- any ideas?


Regards, Oliver