Newbie: glade-2 generated code differ with tutorial

[Edward Yang <neo_in_matrix fastmail fm>]

I am new to gtk+. I am reading the tutorial on gtk site. I also created 
a test project using glade-2 (2.6.8).

But the test program generated by glade-2 cannot close after I click on 
the x window button. After some investigation, I found that the 
delete_event/destroy event handler prototypes are not the same as the 
tutorial states.

I wonder why?