It appears as if rank is stored as a float. The rank can quickly get to be a very, very small number. It seems at some point, float precision might be an issue and/or length of the rank key. Have you run into this and/or do you have solutions?<p>Brandon Keepers wrote about trying this idea in Ruby <a href="http://opensoul.org/blog/archives/2011/09/06/sortable-lists-in-key-value-data-stores/" rel="nofollow">http://opensoul.org/blog/archives/2011/09/06/sortable-lists-...</a> and ran into a float precision issue (see comment).
Maybe I’m using outdated terminology, but why is this called a “rendering engine?” When I think of rendering engines, I think of things that generate pixels.
Back in an earlier version of Meteor I actually implemented drag-sortable and drag-drop lists with jQuery UI and Reactive data sources and it wasn't very difficult. I can't post the source - but there is a simplified demo here: <a href="http://grass-freight.meteor.com/" rel="nofollow">http://grass-freight.meteor.com/</a>