Win8.1 won't let you customize the colors of the tiles anymore. The default (and only) behavior in 8.1 is that it colors the tiles according to central and/or predominant colors found inside the actual program icons. As I noted before this makes the Start and Apps screens pretty much unusable because it throws off your ability to differentiate between program icons (not to mention it is ugly). There's a guy who is working on an app that can fix this and I signed up to be a beta tester for it, so if that takes off I will post something about it here. He said if he ends up not making the app he will release the code so people can use it so I think this should be fruitful. There is, by the way, a way to circumvent this per app but it entails including a manifest file with each app, which of course would be crazy to do.
