This just caused a lot of trouble for me. I had the reveal scroll on my toolbar, but later decided to remove it. Like in any other game with a toolbar, I assumed just dragging it off would do the job. Indeed it did, but it also dropped the item on the floor - unfortunately I didn't notice at the time, and since it's a vital item in the main quest, I had to go arond the whole region with ALT held down until I saw it again.
Basically, it's treated like the inventory UI; dragging an item into the game screen drops the item on the ground. I'd suggest changing this so you're simply moving an icon rather than the item itself.
P.S. Also, please add support for left-handed mouse configuration. Right now it forces right-handedness even if your Windows is set to left-handed.
That stuff aside, I love the game so far.
