gtk_entry question (example from faq)

[Vasiliy G Tolstov <v tolstov selfip ru>]

I'm try to use exmaple from faq
http://library.gnome.org/devel/gtk-faq/stable/x842.html

But then i'm try to compile - i see this error... 
How can i add to entry ability to insert only digits?


window.cpp:214: error: invalid conversion from âvoid (*)()â to âvoid*â
window.cpp:214: error:   initializing argument 6 of âguint
g_signal_handlers_block_matched(void*, GSignalMatchType, guint, GQuark,
GClosure*, void*, void*)â
window.cpp:218: error: invalid conversion from âvoid (*)()â to âvoid*â
window.cpp:218: error:   initializing argument 6 of âguint
g_signal_handlers_unblock_matched(void*, GSignalMatchType, guint,
GQuark, GClosure*, void*, void*)â

-- 
Vasiliy G Tolstov <v tolstov selfip ru>
Selfip.Ru