VISITOR:
On one of the top toolbars there are FOUR buttons next to each other.
The one has a SQUARE in it, the other has a + SIGN in it and the last has a - SIGN in it.
Select the 1st, to SELECT the area. (Blank)
Select the 2nd, to EXPAND to that area. (+)
Select the 3rd, to REMOVE your selection. (-)