[Client] Item Sets dragging and reordering not functioning properly

Dragging an item icon in the Item Sets creation menu places the item at the leftmost position in the item set block instead of where the cursor is. Seems to be a Mac-only issue. OS X Yosemite 10.10.1, Macbook Pro Retina 13" 2014.

Reproduction:

1. Open up Item Sets menu in client.
2. Create a new (or open existing) item set.
3. Place one item in the item set block.
4. Try to drag a second item to the right of the first item. The black vertical line cursor stays at the left side of the first item regardless of where the cursor is placed, and releasing drops the item to the first position.

It's a minor annoyance but still a noticeable bug. Simply reordering an item becomes a Tower of Hanoi-style problem which eliminates the main benefit of having a GUI.