Dragging doesn't actually occur by holding down the mouse button & dragging, it works by left clicking & releasing over the item you want to drag. The term dragging is misleading, as in this case it just means that you are setting the mouse cursor to the same image as the item as if you are actually dragging it around.
If you want to actually drag an item around in the way you want it to work, then you will need to create a custom system with scripting that will allow you to do that.