Selecting a period using arrow keys

During period selection, pressing arrow keys has the following result:

• If the selected period is the first row in the year, pressing Up Arrow has no effect.
• If the selected period is the last row in the year, pressing Down Arrow has no effect.
• Otherwise, the period is set to the month where the cursor is moved (one cell up, down, left, or right from the selected one).

If you hold down Shift while pressing an arrow key, the selected period is not discarded and the selected months are added to the period.