Gtk3: size-request signal is no more, use correct api
correctly destory enum_group
Revert "Gtk3: size-request signal is no more, use correct api"

This reverts commit 06a00876a690711437d30f7183595734298cd603.
Gtk3: size-request signal is no more, use correct api
zero-init signals array
use guint for signals array
don't leak memory