Student can submit after the end of the grace period if the summary page open when the grade period expires

A. Form validation improvements. 1. Go to Site administration ► Plugins ► Activity modules ► Quiz and note the value of Last submission grace period (by default it is 60, I will assume that below). 2. Create/edit a quiz, and try to set Submission grace period to 30 seconds and save the form. You should get a validation error. 3. Try to set Submission grace period to 60 seconds or 1 minute and save the form. You should get a validation error. 4. Try to set Submission grace period to 61 seconds and save the form. The submission should succeed (assuming there are no other problems.) B. Test for the originally reported problem 1. Create a quiz with a time limit of 2 minutes, a grace period of 2 minutes, and When time expires set to use the overdue state. 2. Make an attempt as a student, answer some questions but do not submit. 3. When the count-down timer gets to 0, you should be redirected to the summary page, with a notice about the quiz being overdue. 4. Leave the summary page open for 4 minutes. 5. Click 'Submit all and finish'. The attempt should move to the 'Never submitted' state, since you were too late. 6. Repeat 2-4. then, open the quiz info page in a new tab. This should cause the attempt state to move to the Never submitted state. Then go back to the summary page tab and click the Submit button. The submit should be ignored. You should just be redirected to the review page for the Never submitted attempt. C. Test for a related case found while working on this. Like B. but instead of clicking Submit all and finish, instead just reload the summary page.