What are the vertical edge modes and their differences?
Here's how to observe the difference:
First do either (a) or (b):
(a) Type a few long lines, make sure they're longer than the value under Settings: Set # of Column for Vertical Edge Line. Make sure you can see the lines to this column number.
(b) Temporarily set the value under Settings: Set # of Column for Vertical Edge Line to something smaller than the lengths of the lines you can currently see in a file viewed in NotePad++ -- something like 10 or 20 should work fine.
Now toggle between the two vertical edge modes and watch what happens.
When I do (a) and (b), a thin light blue line appears at the column set in (b). Nothing wraps. In vertical edge background mode, characters after the blue line are highlighted in the same light blue. That's it. And I don't get it.
I got the impression that the vertical edge was functionally a right-margin.
The vertical edge mode <em>marks</em> a right margin for you, but it does not <em>enforce</em> the right margin by wrapping the lines.
Just marking the right margin was especially useful with old-style fortran source files, as the fortran compiler ignored any characters after column 72.