I've been working on an "extension" to the edit page which allows
editors to generate page previews on the fly, directly into the
browser and with no need for page reloads.
I've written a draft with instructions on how to install it which you
can find at:
So far it's still in development and it has some limitations, some of
which I plan to overcome soon, yet I believe it's mature enough to be
useful to some.
Please let me know what you think about it.