Weird effect in unity editor with pixelated outline to objects.

Does anyone know what is happening here? Its been like that for a while and is starting to get annoying. I have the unity scene view open with a camera frustrum selected. It only happens when I am modifying a prefab and have an object selected. Ive tried turning off things like gizmos but its still there. As far as I can tell the issue is graphical only. Thanks