[gtkmm] Comments on tutorial

[RMM <morelli cs utah edu>]

I just took a quick look at the gtkmm tutorial (Programming with gtkmm2)
and have a couple of comments.  Since I'm writing something like a
drawing application,  I jumped right to chapter 14,  The Drawing Area
Widget.

First,  the example program (presented in)
http://gtkmm.sourceforge.net/gtkmm2/docs/tutorial/html/ch14s03.html
has a comment in the declaration of CustomDrawingArea:

   //TODO: Why do we store m_width and m_height?  murrayc

which makes no sense in its context.  I assume this code was already
fixed,  or it was copied from somewhere where it might have made sense.

Second,  the main method contains the unexplained line:

Gtk::Main main_runner(argc, argv);

Looking back over previous chapters,  I see the line

Gtk::Main kit(argc, argv);

in the corresponding place,  which is explained in the beginning of the 
tutorial.  I notice that the author of chapter 14 (M'Sadoquesis) is
different from the author of the previous chapters,  which may help 
explain this.  Someone needs to advise the author of chapter 14
to get in line with the previous chapters.

Another thing that surprised me was that there was no interactive 
example in the chapter,  such as a drawing application,  or at least
something that responds to a mouse click or anything.  I think of that
as a sort of hello world for canvas type widgets.

Instead of dealing with normal interactive events like mouse events,
the example programs are all built around around responding to the
expose event (in on_expose_event).  Why?  On first impression,  this
strikes me as rather strange.

Thanks,
RMM