[cybmole]

i did not know about the calibre plug in but what I do is find the book in calibre library, then click where it says path: click to open ( under the book picture). I have made sigil the default program for epub so when I thes double click the .epub file, it opens in sigil.

I also keep a backup of the calibre library so if I mess up the book with sigial I can restore a previous copy.

if you want to do even more, ther's a free app called microspell which works with sigil as a spell checker - that helps with finding typos but it takes a bit of getting used to. serach forums for sell checker for more info.

my current preference is to keep a notepad handy when reading an ebook & jot down any particularly annoying typos, , unwanted linefeeds etc. so that I can fix up the epub later without breaking up the reading experience.

If there are lots & lots of them, I used to convert the book to .rtf format & fix it up in Word, then convert back to epub afterwards , with calibre.
that's maybe an overkill method but it needs no programming skills!
I try now to do everything with sigil & microspell, & learn those programs better as I go.