We need a checkbox for it in the stroke properties tab.
Currently I think it's a compile-time flag, which means it's unusable for most users.

I'd love to highlight this feature in the Inkscape video at LGM.

Can someone add this?

For reference as to what it does, look here:
https://plus.google.com/+inkscape/posts/QBxB6CDhNzZ

Thanks. :)

-C