Click here... displayed instead of 0 in mark details in Quiz Report 'Overview'

link_to_popup_window displays 'Click here....' as the link text if you pass in 0 as the link text.

Solved this by formatting the grade using number_format to display the grade with a number of decimal places. So for 0 we display something like 0.00 and this displays OK in link_to_popup_window.