Works properly- drag to folder, it snaps to top.
Works correctly with BSP2 and QuickBookmarkToFolder.
Dragging between BSP2 lists in tab and sidebar, it places at top if droppped on a folder, or at the position where it's dropped in a list.
Dragging to position in Bookmarks toolbar dropdown snaps it to the top, click the icon to turn it off.

It only toggles on or off AFAICS (it's set to 'ask' in the options by default- access through addons, options) - but I wouldn't need 'ask' anyway, the on/off toggle is right there.