>   ffi_lib 'user32', 'msvcrt'

Hmm.
This code:

require 'ffi'
module M
 extend FFI::Library
 ffi_lib 'user32'
 ffi_lib 'msvcrt'
 attach_function 'FindWindow', [ :string, :string], :pointer
end

yields this response:

C:/installs/ruby19_mingw/lib/ruby/gems/1.9.1/gems/ffi-0.5.4-x86-
mingw32/lib/ffi/library.rb:77:in `attach_function': Function
'FindWindow' not found in [msvcrt] (FFI::NotFoundError)
        from go2.rb:6:in `<module:M>'
        from go2.rb:2:in `<main>'

I assume this is unexpected?
-r