gdk3 test: In Gdk Event, #send_event?, #in?, #implicit? and #keyboard? are not defined.

Currently, in Gdk Event, #send_event, #in, #implicit and #keyboard are defined.
These are not Rubyish methods naming....
gdk3 test: Gdk::Window and Gdk::Pixbuf module are not defined.

Currently, Gdk.default_root_window and Gdk.pixbuf_get_from_surface are
defined unexpectedly.