Tell me about difference between g_signal_connect and g_signal_connect_after

[Cool Guy <assa77 gmail com>]

In reference,

g_signal_connect : The handler will be called before the default handler
of the signal.
g_signal_connect_after : The handler will be called after the default
handler of the signal.

But, I don't know why is different g_signal_connect and
g_signal_connect_after.

Where is example about difference or explain them?