I want to make a layer in gimp, that is just an image that doesn't cover the whole background, but I don't want the rest of the layer to be a transparent surface. I want the layer to end with the image of, say, a dog or a basketball, without any transparency around it. How do I do this?
Edit: To clarify since many misunderstood what I'm looking for, I want the layer to stop with the outline of the figure, beyond which you cannot draw on that layer.