I have found a bug in dewidow. I noticed that some lines disappear. I have found that commenting line
$unlockedText = $this->dewidow($unlockedText);
I identified which lines are killed by the function.
These are utf-8 encoded lines that ends with 2-byte C2 A0 sequence (non-breaking space).
<li>some text [C2 A0]</li>
appears on page as