Rendering of single-value select boxes is misleading. We think that several projects can be selected at the same time. But that's not the case, for example when I click on PL/I in the attached screenshot, Fortify is unchecked
Could we use radio-button style ? I know that the goal was to show that everything can be unchecked, which is not allowed by standard radio buttons, but it does not worry me to be able to unselect a radio button.
All that to say, I suggest to replace the square by a radio-button circle, without changing behavior