patch for "Programming with GTKMM" book

[Gezim Hoxha <gezimetc shaw ca>]

Hi,

In http://www.gtkmm.org/docs/gtkmm-2.4/docs/tutorial/html/ch17s03.html
there is a "request_methods()" function method mentioned, however I
think the method that the author meant is "request_targets()".
Therefore, here is a patch that can be applied to that file.

56c56
< <code class="function">request_methods()</code> method, specifying a method to be called
---
> <code class="function">request_targets()</code> method, specifying a method to be called