Furthermore, the folder then remains open, often obscuring all the other bookmark-sidebar folders until it's manually closed.
 And finally, if the bookmarks sidebar isn't even open, this drag-across activity will often open BOTH the bookmarks sidebar AND whatever folder was the dragging cursor's accidental victim.
 It's fine to have this folder pop-open as an OPTION, but it would be MUCH preferable to have the OPTION to shut-off this behavior.

Bookmark folders in the bookmarks SIDEbar pop-open if an image is dragged across them not-quickly-enough. This is true even if the image is being dragged from, say, the Finder's desktop over to another Finder location or Finder folder, or to some other application (e.g. to be dropped into a Filemaker record) - and merely passing-over a Firefox window that happens to also be open though NOT being the active app. I'm told by Firefox support that there's no way to disable this "feature". Furthermore, the folder then remains open, often obscuring all the other bookmark-sidebar folders until it's manually closed. And finally, if the bookmarks sidebar isn't even open, this drag-across activity will often open BOTH the bookmarks sidebar AND whatever folder was the dragging cursor's accidental victim. It's fine to have this folder pop-open as an OPTION, but it would be MUCH preferable to have the OPTION to shut-off this behavior.