I'd like to mark examples, in an
example environment in the text by drawing a vertical bar along the margin. I found a piece of code that uses the
framed package to do this, but since the content of the environment in a box, this doesn't break across pages.
To show the example will continue on the next page, the line should extend vertically a bit further before/after the page break. That shouldn't be a problem using tikz, if one manages to place coordinates at the first/last lines of the environment and at the lines before/after each page break. It looks like Martin Scharrer was working on something like this, but I haven't found if that's ended up in a package by now…
In my case, I need support for at most one page break per environment.