I find the following behavior in Firefox, not in IE or Chrome or iOS...
When a playlist item is dragged to a new position, on release of the mouse in Firefox the dragged item becomes selected and starts to play. If the dragged item is already playing, play starts over at the beginning of the track. (If another item was selected beforehand, whether or not it was playing, it becomes deselected at the same instant.) Perhaps this behavior could be called "oops" behavior.
In IE or Chrome or iOS, item selection is not affected by dragging, whether or not already playing. This behavior is preferable - perhaps it could be called "quiet" or "discreet" behavior.
I have done a bit of homework on this. It seems that Firefox requires an additional jQuery instruction along the lines of "prevent default behavior when the mouse is released after dragging" to prevent the oops behavior.
Does this make sense? And if so, where would the additional instruction be inserted and how would it be written?
(Autoplay is set to off. Module height is set to auto, which removes the need for the playlist scrollbar to appear. To be certain the playlist scrollbar does not re-appear in connection with dragging of items, display of the scrollbar is set to none via css. I am also using css to prevent the dragged item's margin-top from changing as a result of dragging. These are personal preferences - I don't think they are relevant to the question, though they might make it easier to reproduce the behavior I am describing).