Are you asking whether I can add additional buttons? Or whether you want to be able to do this? In any case, it’s possible in principal but it requires editing BlogText’s source code. There’s no option for that, if that’s what you’re asking.
Adding a button for headings would be easy enough (although I doubt it would be used a lot because heading are fairly simple to write).
As for the button for tables: it’s highly unlikely that I’ll add this because this would require some kind of elaborate dialog. As far as I can estimate it, the effort required to create such a dialog would be immense (and IMHO far outweigh the benefits).
I hope this helps.
