To add months to a period, hold down Shift while clicking that month. This has the following effect:
- If the selected month is later than the selected period, the months between the last month of the period and the selected month (including the selected month) are added to the period.
- If the selected month is earlier than the selected period, the months between the selected month and the first month of the period (including the selected month) are added to the period.
- If the selected month is inside the period, there is no effect.
- If the period is not selected, it is the same as setting a period without holding down Shift.
If you hold down Ctrl while clicking a month, this has the following effect:
- If the selected month is adjacent to the period, it is added to the period.
- If the selected month is the first or the last month of the period, it is removed.
- If the period is not selected, it is the same as setting a period without holding down Ctrl.