e', onMouseDragged, false);
  };

  let onMouseDown = (e: React.MouseEvent<HTMLElement>) => {
    const target = e.currentTarget;
    // If we're already handling dragging on a descendant with useDrag1D, then
    // we don't want to handle the drag motion on this target as well.
    if (draggingElements.some(elt => target.contains(elt))) {
      return;
    }
    draggingElements.push(target);
    window.addEventListener('mousemove', onMouseDragged, false);
    window.addEventListener('mouseup', onMouseUp, false);
  };

  let onMouseEnter = () => {
    if (onHover) {
      onHover(true);
    }
  };

  let onMouseOut = () => {
    if (onHover) {
      onHover(false);
    }
  };

  let onKeyDown = (e) => {
    switch (e.key) {
      case 'Left':
      case 'ArrowLeft':
        if (orientation === 'horizontal') {
          e.preventDefault();
          if (onDecrement && !reverse) {
            onDecrement();
          } else if (onIncrement && reverse) {
            onIncrement();
          }
        }
        break;
      case 'Up':
      case 'ArrowUp':
        if (orientation === 'vertical') {
          e.preventDefault();
          if (onDecrement && !reverse) {
            onDecrement();
          } else if (onIncrement && reverse) {
            onIncrement();
          }
        }
        break;
      case 'Right':
      case 'ArrowRight':
        if (orientation === 'horizontal') {
          e.preventDefault();
          if (onIncrement && !reverse) {
            onIncrement();
          } else if (onDecrement && reverse) {
            onDecrement();
          }
        }
        break;
      case 'Down':
      case 'ArrowDown':
        if (orientation === 'vertical') {
          e.preventDefault();
          if (onIncrement && !reverse) {
            onIncrement();
          } else if (onDecrement && reverse) {
            onDecrement();
          }
        }
        break;
      case 'Home':
        e.preventDefault();
        if (onDecrementToMin) {
          onDecrementToMin();
        }
        break;
      case 'End':
        e.preventDefault();
        if (onIncrementToMax) {
          onIncrementToMax();
        }
        break;
      case 'Enter':
        e.preventDefault();
        if (onCollapseToggle) {
          onCollapseToggle();
        }
        break;
    }
  };

  return {onMouseDown, onMouseEnter, onMouseOut, onKeyDown};
}