Using the cloning brush in texture painting mode

I am currently working on a scene where I was planning on texturing a small house via projection UV mapping (sorry I don’t know the official name of the tool). I was then going to clone over the main parts to a normal UV map and then edit it externally. However, upon entering texture paint mode the cloning brush is not present as an option. I read about the subject in the blender wiki but I could not find any help there. Did I miss something or is this some strange glitch?

Thanks in advance :smiley: