Help with closing a notebook page (GTK2)

[Neil Munro <neilmunro gmail com>]

Hi, I have used pygtk before so I am familiar with some of the basic
concepts of gtk, but this is my first attempt with an actual gtk+ C
application and I have run into a few issues.

I have a notebook that I wish to have a close button on the page tabs
that when clicked closes the tabs.

I know that it's a bit off a faf to do as you don't know the page
prior to the event. So you have to dynamically detect which tab is
being closed by using a tab child widget.

Now I believe I have done this in code, except it always returns -1
which then firmly tells me I have done something wrong.

I have attached the code for your reference in the hopes that someone
shall be able to point out my no doubt simple mistake.

Many thanks in advance,
Neil Munro