To simplify your Meal-planning process, use the Meal-tray to arrange food into various meals of a day (be sure to have the tray on the table in a visible area before opening the Meal-planner screen), and drag the tray into a selected day in the plan. Once in the plan, the a rectangular box appears to represent the tray; let go of the mouse at a plan entry to drop food (a confirmation box will appear).
