Today when I started Visual Studio 2012 at work I found some new colored bars.
We work on a shared remote server through RDP, so I asked around if someone has instal
They come from the GIT source control provider. I suppose your project is versioned, so those bars give you information about lines that are changed in some way, and what is the nature of the change.
Go to Edit menu Advanced / View White Space Ctrl+E,S