The current session support of PHP4 is pretty bad. I dont mean to be insulting or anything, but the session functions like session_start() and session_register() are too high level. 

It would make more sense to do it this way:
session_start() start a session. thats it. no setting of variables - just init a new session id, and start passing it between pages with cookies or get variables.

session_pickup(variablename,[session id]) set the local variable(s) and make it so that if any of those variables get changed, the changes get made to the session (if i pickup where i left off, and i change some of those variables, I want my next page to know about it). If no var name is specified, maybe pickup all of them

session_register(variable name, [session id]) register a session variable.  This makes it so that the variable gets lugged around with the session and if changes get made to the variable on another page, the new value is propigated.

session_variables(session id) - similar to array_keys() returns all of the variables held in the session

session_end($session id) ends the session, unregisters everything

session_unregister(variable, [session id])  stop propigating a particular variable

session_lock(variable, [session id]) make it so that a variable in the session is read only - still gets propigated, but cant be changed

session_unlock(variable, [session id]) unlock the variable, let it be written to

But you get the drift, more stuff like this, more broken down, more low level commands to do stuff with sessions would be nice - but the ability to actually change session variables values easily would really be nice. :)

Get what I mean? :) Thanks a bunch :)