How to approach this?

[Dirk Schippers <lua@...>]

Hi,

I am creating a test project (C++) where I have this telnet server which 
creates a thread for every connected client that has its own Lua 
environment to play around in.
But I want to do more than: print 5 + 2
So I created some functions: createWindow({...}) which creates a window. 
I can call it multiple times to create multiple windows.
At this time, the function has become the constructor for an object, 
which returns a light userdata pointing to a C-struct containing the 
window handle and some other stuff.
But I want to expand this: I want the return value to become a table 
where you can put your own events handlers in, like this:
w = window.new({...})
w.onMouseMove = function(x, y)
    ...
end

I would also like to be able to pass the event function immediately to 
the constructor as well but still keep the ability to update the event 
later on.
Now the question is, how do I handle this: do I create a table (instead 
of a light userdata) in the constructor for window and add a metatable 
to it? How should I handle the optional event declaration? Do I need to 
override the __index or should I keep all of it in lua? How can I call 
the correct event function in the correct object when I receive the 
events in my message loop? If I use tables, I don't know how to find 
them back... How can I keep an index between the window handle and a lua 
table?
Where do I put the window-handle and stuff like that, whilst keeping the 
table safe so that noone can change this window handle through Lua code 
and corrupt the environment? Do I put an extra light userdata inside the 
table? Can I protect that one?
I know this is a big question but I have the feeling that the answer 
will be simpler.
Dirk.