Consider this case
A student has 4 assignments have been marked as:
I set four of them in a new category called myCategory, and hides any other category. So only myCategory will be displayed.
I set the Drop X Lowest to 1. That should drop Assg4 (since it's the lowest). so Total is 150.
The problem comes when I exclude an assignment and still leaving the Drop X Lowest to 1. Say, I exclude Assg4. So I am expecting the total mark to be 110, because Assg4 is excluded and Assg1 should be dropped from the grade since it's the lowest mark.