There isn’t that much latitude - the “up reversal” and “essential” options don’t really apply here. That only leaves “Abort or Undo”. The concern here is with UIs feeling snappy, so we’re not talking about the type of long-running task where abort applies, which leaves Undo. So - no longer is it a simple matter of “just use the mousedown event, stop overcomplicating UIs by adding things like long press and drag/drop that force you to use mouseup events”, it’s a much more complicated matter of “use the mousedown event and also implement a comprehensive undo system”.