mouse pointer and browser

Hi

I;m curious to know how a browser application will change the mouse pointer from arrow to a hand when the mouse pointer is above a link for example. Do you have any idea about how can I know at every moment what type of mouse pointer do I have to deal with? I was thinking at using a mouse hook. What do you think?

so, I need to know:
1) how the browsers tells to the OS what mouse pointer type to use?
2) how can i know at every moment what mouse pointer is?

many thanks