Wiki textarea autocomplete?

Hi everybody,

I'm tring to develop a widget, to provide autocomplete function to the wikitools textarea, for example:

When I type in '[[D', it will look for all wiki pages whose titles start with D, and list all the options in a floating select box.

I've done some searching, and find nodereference and autocomplete very helpful, but since autocomplete is just for text fields, not textareas, I would like to ask if it is possible to write such a widget or module? And if yes, could you give me some hints on it? Just for me to get the right direction :)

Thanks a lot