It can be done with Javascript, but the saving process it's not just writing data in database. It's a whole process which must check the current revision and permissions, validate the input, give messages (success or error). In a few words, similar to what is already done by the controller of textblock_edit. The visual effect is almost the same I was done with this patch (except that, after "save and edit", the text will not be scrolled again to the top), but a lot of code must be written for this. And most of it, duplicate code (copy-paste with slight differences).

I submitted this solution because it was low-cost to integrate it and it gave the desired results. If you think that Javascript would give a better solution, you can reopen the ticket and I will make it again.

As a side note to all devs: when you commit please say what you did in the changeset and don't leave the field blank. Also, please specify if it was reviewed and the review link.