Dragged Item

The dragged item is the picture that follows your cursor while you carry something. It shows the item you picked up, or the action you picked up from a list or a hotbar. When you carry several of an item, such as part of a stack, its count stands beside the picture.

Dragged Item, arrows — Forty arrows carried over the world, from a stack of 150. The top-left corner of the picture hangs from the cursor, and the count "x40" stands to the left of it.

Opening it

It appears when you pick up an item or an action.
It goes away when you drop what you carry or put it back.

Using it

Move the mouse to carry the picture where you want it. It hangs from the cursor by its top-left corner.
Drop it on a window, a slot or the ground to put the item or action there.
It takes no clicks of its own.