Who tries livePreview for nsPage, finds that it's no so much comfortable, since size/position of its output doesn't allow a useful comparison with front image or with wikicode. VisualEditor could be a good solution, but presently it have limitations dealing with wikisource nsPage, mostly when adding fastly complex format, without the help of our beloved tools.

Here: https://it.wikisource.org/wiki/Utente:Alex_brollo/livePreview.js a temptative js code to customize the output of livePreview for wikisource needs: output goes into a box superimposed to edit area, draggable if user likes a comparison with wiki code, instead of a comparison with front image.

Far from being a professional script, it is just to proof that* it can be done. * If there's any better solution for that issue, please tell me!

Alex brollo (from it.source)