Space characters are not shown at the end of lines of text in the area where
word-wrapping occurs (with display of Nonprinting Characters enabled).  This is
irksome when trying to enter text at the end of a line.  Clicking at the end of
a line causes the cursor to be placed immediately against the last character in
the line, regardless of how many spaces may appear after it.  Intuitive
behaviour drives you to attempt to enter a space after that character to provide
separation for the next word, but since spaces are not displayed there, you end
up entering many.  Unable to see them, you are unable to delete any extra ones.
 If you then enter a word, all formatting seems fine, until any subsequent
editing of the paragraph causes word-wrapping to occur in a different place,
whereupon the extra spaces (and the attendant disjointed formatting) become
evident.  This behaviour is inconsistent with other non-printing characters,
such as the Tab character.  If you enter a Tab character at the end of a line,
it is displayed immediately (provided that a tab stop appears after the cursor
position and before the right page margin).  At the same instant, any existing
spaces that may have been between the cursor and the last character on the line
are also displayed.  It would seem more logical and more user-friendly to make
the spaces appear at the end of a line at all times.  If there is an issue with
not being able to draw all the spaces because they would extend past the page
border, then just display those that would appear before the page border.  Extra
spaces would then become immediately obvious because they would stick out past
the page margin to the page border.  I class this as a defect because the user
has set Nonprinting Characters to be displayed, and in this case, they are not.