Metro applications can have a colour set, which appears on their shortcut on the start screen, and also on any dialogs and UI elements, so users can recognise the application, for example helping them associate toasts with the source application quickly.
So far so good. Traditional shortcuts to desktop applications also appear on the start screen. They don’t have a colour, and any toast notifications they send have a grey background. Microsoft’s own applications such as VS2012, redone in semi-metro-style, also have a colourless start screen tile.
How can a colour be set for the start screen shortcut, or toast notifications, for a desktop application?
For desktop apps, the background color used on Start screen tiles and toast notifications is not configurable by the app itself. The color is determined by the Start screen color theme chosen by the user (PC Settings -> Personalize -> Start screen).