Take a look at includes/adminfunctions.php

There are a lot of print_ functions which are being used to construct CP dialogs.

Can you recommend any advanced php books?

No, sorry - haven't read any books about PHP so far :)

All online tuts?

I also haven't read tutorials - LOL.
The online manual (http://www.php.net) and sometimes Google was always enough :)

Lol. I preffer books. I'll look @ that again, everyone says to look @ it. When I looked @ it I got a little confused, gota try again :P...
Thanks.

I think sitepoint.com has some good books.

personally i dont rate php books, the one i used; most of the code examples were incorrect i ended up spending hours on php.net working out what was wrong... looking at that perhaps it helped me learn :s

To understand vb a bit better i believe zach has a link in his sig you may find useful.

https://vborg.vbsupport.ru/showthread.php?t=59939

Read that. It helped alot. Do you know of any other article similar to that?

Read everything you can in the modification tips and tricks forum.

A basic understanding of php will get you very far, it is alot easier to modify something when you can understand exactly what is going on ;).