dragging folder block not working in FF 23 (on Win7 x64) neither FF x64 Nightly Rated 5 out of 5 stars

most of 6.12 now working in FF 23 and Nightly x64
But unfortunately Not:
'modify layout with dragging folder block'
(works in 1st Column)

('modify position of a bookmark item with dragging link', does work)
could you please have a look at this

This review is for a previous version of the add-on (0.6.8.1-signed).  This user has other reviews of this add-on.