Re: @dogged
"If MS had removed the "theming code", Start 8 could not exist."
They didn't remove all of it, just the bits Metro didn't need and the code to read many preferences. In prerelease builds much of it was just a regedit away from resurrection, then they excised the code they didn't want anyone using.
Through subclassing pretty much anything can manipulate the UI. Having to install a 3rd party theming driver to actually do that is a security hole waiting to be exploited.