[CLIENT] Item Sets is buggy on Mac client

Dragging-and-dropping items onto an Items page fails to work as expected. You can only drag an item onto the beginning of a block, which requires you to manually shuffle the items when you wish to drop an item halfway through a block.

Steps to reproduce:

1. Log into the client.
2. Visit the Item Sets page.
3. Create a new item set, and a new block.
4. Add a few items to a block, then try to insert an item to the end of the block.

Also, there is an intermittent bug that happens when the description text of an item covers up a block and prevents you from dropping the item onto that block completely. Since the first bug exists, this becomes more annoying.