I had a Mac user chew me out for putting on a non-Apple mouse that JUST DOESN'T WORK ON MAC!!!1! Found out that he'd used the non-Apple mouse fine for about a month, then changed his desk to one with a glass top, and wasn't using a mousepad. So the laser just shot through the clear glass and did fuck-all. Didn't even have the decency to look abashed when I tossed a magazine down as a mousepad for him until we could get him some artist-approved mousepad bullshit. Fucking ad agencies are full of twats.