I am panning in the editor in my [3D] scene by holding the right-mouse button. When the cursor goes offscreen it wraps to the other side of the screen. At that point, the camera pops as if I were viewing the scene from that [relative mouse-] position.
i.e pan to the right until the cursor wraps to the left side of the screen or pan down until the mouse wraps to the top of the screen. Left/right causes the camera to ~180 and suddenly the camera is looking backward from where I expected. Up/down causes the camera to ~180 and suddenly the entire scene is upside down and the camera is looking backward.
This only happens sometimes, approximately 75% of the time. It always happens the first time the mouse wraps. This is highly annoying and makes it very hard to look where I want to look in a consistent manner.
Unity v5.1.1f1