As a cord-cutter, I do all of my TV show watching on demand as I'm sure many others do. The Calendar view is one of the best resources you have for keeping up with current shows that you want to keep...well, current. And while I am a big fan of the subtle highlighting you've added to allow us to see at a glance what shows have been watched, for me it's a little *too* subtle. I don't know whether it's my old eyes or my TV (which doubles as my monitor) is too bright but most of the time I have to really look to see what I've watched and what I haven't. Having an alternate theme that makes the highlighting a little less subtle would be a fantastic help. Now whether you'd want to go whole hog and make things customizable with different themes, make the colors customizable by the user or just have a switch to a more "high contrast" color scheme would be totally up to you depending on how much work you'd want to put into it. I hope I'm not just being a picky old fart but I'd just like to be able to tell what's been watched already a little quicker and easier. ;-)
