For the moment it spawns a separate window and seems to behave nastily
    (read: crashes) when the target has sound, but the javascript interface
    works perfectly, for instance.

    To build it, I installed Mozilla development files in my mingw32 dir
    and hacked mozilla-config so that it uses these files. I also hacked
    jri_md.h and jni_md.h to put "defined(_MSC_VER) || defined(__MINGW32__)"
    where it read "defined(_MSC_VER)". No other changes were necessary.