g_signal_connect_swapped

[Richard <rileyrg googlemail com>]

Could someone explain the reason for this function

"g_signal_connect_swapped"

I have read the manual here:

http://www.gtk.org/tutorial/x159.html

where it says:

,----
| g_signal_connect_swapped() is the same as g_signal_connect() except that
| the instance on which the signal is emitted and data will be swapped
| when calling the handler. So when using this function to connect
| signals, the callback should be of the form
| 
| 
| void callback_func( gpointer   callback_data,
|                     ... /* other signal arguments */
|                     GtkWidget *widget);
| 
| where the object is usually a widget.
`----

Could anyone express this a little clearer? I (as a gtk beginner) can
see no reason for it.