I hope this hasn't been addressed before (a quick search didn't turn up anything).
One of the most common formatting errors in etexts is inappropriate line breaks. When correcting these in Sigil in Book View, I generally add a space at the end of the line, then hit delete. However, Sigil inserts an $nbsp; instead of a normal space, which is not, of course, what I want.
I'm new to Sigil, so I'm sure there's an easy fix, I just don't know what it is.
EDIT: Forgot to say. I'm using Sigil 0.2.3 on Ubuntu 10.10b x64.