I would like to make tinymce an option alongside xinha. I'd like it to be consistent with xowiki and the rest of the richtext areas across the site. To do that I'd need to change the code that generates the form in xowiki-form-procs.tcl It seems pretty easy to do that flexibly.
The back button problem is subtle. If you are editing content and for exmaple, you browser session expires. You may be reidrected to login when you submit the form. In xinha, if you then hit the back button to go back to the screen to edit the content, the xinha textarea is empty.
TinyMCE handles this correctly. I submitted a bug for Xinha but it has not been fixed yet.