PUZZLE 063 The Unopened Room

This is a closed room that no one ever enters.
However, one year has passed and it seems that something in the room has changed.
What is it?
Slide the circle over the thiing that you think has changed.

Hint 1

Nobody ever enters the room, so the position of the objects can't have changed.

Hint 2

It is one year later that the room is entered again.
What could have changed in that time without being moved?
Is there anything nearby to give you a clue?

Hint 3

The things that has changed is a matter of volume.

Super Hint

The contents go down with each passing day.
It's inside a clear container, so you can easily see if the contents have decreased.

Answer for 'The Unopened Room'

The answer is 'The bottole full of the water on the desk'.