Dear Joseph,
This is a small example to make it work (compile it with g++ gtk_layout.cpp -o gtk_layout `pkg-config gtkmm-3.0 --cflags --libs`):
Some servers like, for example, "Debian Paste" gives you the possibility of sharing your code in a more readable way:
https://paste.debian.net/1160914/
Cheers :)
Aitor.