On the other hand, the code pane modification can be made within an hour (maybe two if you are not confident with morphic, but it doesn't seems to be the case) using the plugin mecanism (Johan Fabry can testify ^^).
Then, Nautilus is not cross platform, but we have developed Spec with the goal to use it for Nautilus, and Spec is(will be ^^) cross platform. So one day, Nautilus will be cross platform. Sadly, I will not be soon (I have to rewrite the whole ui).