RE: unobstrusive way to show indentation

[Drew Adams]

> How difficult would it be to implement some way to show
> indentation levels in an unobstrusive way?  Sublime text
> and other modern editors do this by drawing a thin
> vertical line down from (back-to-indentation).  I find it
> really helpful when reading code.  This stackoverflow
> question clarifies what I'm after, although I didn't ask it.
> I find this really helpful when reading a piece of code
> with many block levels, especially since the standard
> indentation level for ruby is 2 spaces.
>               
> I guess it can be faked by changing the face of that column,
> but that would be more obstrusive than a thin line.  Maybe
> there is another solution I haven't thought of? 
>
http://stackoverflow.com/questions/8836336/sublime-text-2-like-block-highlightin
g-in-emacs

It's not quite the same thing, but you get a similar benefit from the features
mentioned here:

http://www.emacswiki.org/emacs/HighlightCurrentColumn
http://www.emacswiki.org/emacs/VlineMode

Vline can use a thin line (or a face). Column-marker highlighting stays put
(doesn't move with the cursor), and you can highlight any number of columns, but
it uses a face, not a thin line.