g_main_loop and persistant connections

[Matí­as Alejandro Torres <torresmat gmail com>]

Hi, I'm having problems to design a python network application, that is 
like a messenger.

In this app, the user would be able to send and receive messages. There 
are persistant connections involved, mainly because it is possible to 
receive messages asyncronously.

I would like to handle these permanent connections in differents 
threads, so the GUI doesn't halt when sending, receiving or even 
wainting a message, but....

*How the main thread (the GUI, locked in g_main_loop) is awaken by the 
connection handler threads when a message arrives????
*
I don't understand how the connection threads call functions that should 
be run in the main thread when this one is iterating the main loop. *Can 
different threads make modifications in the widgets?* (using the 
appropiate locks, barriers when needed).

Can someone point to a nice howto/tutorial about this? Any help would be 
appreciate since I've never written an application like this and I am 
kind of fully-lost about this.

Thanks in advance, even for reading up to here.

Matías