I upgraded to FreeBSD's latest version of ruby.
> ruby -v
ruby 1.8.1 (2004-05-02) [i386-freebsd5]

Now, some of my Ruby/Tk applications won't work anymore.
The problem seems to be this.

cmd = proc{
  puts "a"
  Thread.new{
    sleep 10
  }
  puts "b"
}

TkButton.new{
  text "Push"
  command cmd
  pack
}

When running cmd.call i get the printout "a" and "b" quickly. The new Thread
is just sleeping quietly in the background.
However, when I push my TkButton, I get the "a", then the whole program
sleeps for 10 seconds, then I get the "b". So something is really strange
here. I had no problems with the code above in earlier versions.