Strange thing with method lookup

[Michel Demazure]

It happens in a quite complex fxruby application, and I am not able to
extract it in a simpler form.

I have a utility function on Fixnum, say 'foo'. When I define it by

module MyMod
class ::Fixnum
def foo ; ... ; end
end
...

everything works. When I define it by

class Fixnum
def foo ; ... ; end
end
module MyMod
...

the thread which calls it hangs silently. It happens with this method
alone, I have other methods on Fixnum, Array, Hash ... which do not care
which way I define them.

This is ruby 1.9.1-p.378 and fxruby-1.6.20 on WindowsXP (mingw).

Ideas ?