This is likely not limited to just S&D. The paperclip difference of green/medium gray is not as noticeable as one may think, considering that the clip is only 1 pixel thick. One of my coworkers is partially color-blind and this is causing problems with seeing the difference between documents present or not present. I think a simple solution may be to use a gray that is 30-50% lighter so that there is greater contrast. That or the entire button could change colors as it does on the old-style chain link.