Please explain five stages of signal emission(gobject).

["DC A" <adc4444 hotmail com>]

Hi! First of all i want to say I'm trying to learn gtk+2.0. And I got stuck 
at a section(GObject's signal api) where they mentioned that A signal 
emission consists of five stages which are:


1 - Invocation of the object method handler for G_SIGNAL_RUN_FIRST signals
2 - Invocation of normal user-provided signal handlers (after flag FALSE)
3 - Invocation of the object method handler for G_SIGNAL_RUN_LAST signals
4 - Invocation of user provided signal handlers, connected with an after 
flag of TRUE
5 - Invocation of the object method handler for G_SIGNAL_RUN_CLEANUP signals


My questions are:

1)what is this 'after flag'?
2)Can anyone kindly give example and explain of a signal that goes through 
these five stages?
3) what is the difference between object method handler and user-provided 
signal handler?


Sorry for my ignorance but i spent 3 days to get info on this (on web, 
books, API, reference, docs etc. and those that are there i don't understand 
them).
Any help will be highly appreciated.

Thanks.

--TLo1