[gtkmm] book: DrawingArea chapter finally updated

[Murray Cumming Comneon com]

For a long time, the DrawingArea chapter was the only part of the gtkmm book
that was not updated for gtkmm2.

A lot of people complained, and a few people made small fixes, but Ainsley
Pereira actually updated the examples and some of the text:
http://www.gtkmm.org/gtkmm2/docs/tutorial/html/ch14.html

So, it should all be OK now. Tell us if it isn't - probably in bugzilla.
Thanks, Ainsley.

Murray Cumming
murrayc usa net
www.murrayc.com