custom widget tutorial example

[scharloi numericable fr]

Hello,

Newbie in gtkmm programming, I have compiled the widget example
(Chapter 21 of the "Programming with gtkmm" online book) on a
win32-XP OS using the Mingw compiler and gtkmm2.6.

The example implements a widget which draws a square.

The problem is, the widget doesn't show.

What's wrong with this example ? or did I forget something ?

Thanks for any help.