When you bring a sticky note close to the edge of a monitor, it will stick to it.
You can also stick sticky notes together.
In this case, if the side to be attached is A and the side attaching it is B,
when you move the attached A, B will also move.
To release the attachment, move B on the attached side and the two will separate naturally.
This may not be the case very often, but if you attach B to A and C to B,
when you move A, both B and C will move together.