A Day Late, and a Dollar Short

How many of you have grabbed a handful of CD jewel cases to go in the car, and when you open them up, one or more of them are empty? So annoying. My invention would be to have some kind of window in the cover art, so you can tell at a glance if your CD case has a CD in it. 

This didn't seem to be as much of a problem with record albums, perhaps because vinyl records were less portable in the first place, and a record sitting on your turntable was pretty obvious. But a CD pretty much disappears into your CD player drawer. 

It's too late now, since CDs have become more or less obsolete anyway, and millions of CD cases already don't have my brilliant invention. Too bad. So sad.