python - Tkinter can't change multiple selections in a listbox

Question

im trying to create a "to-do list" app that can keep track of time. if the task hasn't been done by a certain date then the task would change color. the problem is i can't seem to be able to select multiple tasks and change their color the print statement at the end is just to check if the function works

the code=

list1=tkinter.listbox

what_to_color = []

def check_date():
    for i in list1.get(0,tkinter.END):
        current_day = datetime.date.today()
        days_to_pass = 1
        end_time = datetime.timedelta(days=days_to_pass)
        end_date = current_day + end_time
        root.after(555, check_date)

        if end_date == current_day + datetime.timedelta(days=1) and i not in what_to_color:
            what_to_color.append(i)
        print('needs to color')

Answer 1

等待大神答复