why get_currentuserinfo() work in themes,not in plugins..

Hi,

I’m writing a widget that I can put somewhere (e.g.) the sidebar that gives the option of logging in on frontpage. That works btw.
But, when logged in, I also like to display the current logged in user’s info through the get_currentuserinfo()-function.

This doesn’t work.

However, when I e.g. call that function in a theme file, it works.

How can I resolve this ?

My final goal is to make a dropdown slider (Justin Tadlock’s plugin) where I have three columns,
1. user info
2. register
3. login

So users can login or register that way, and when logged in, see their info there or go to ‘their profile’..