In the example, start with the mouse at the bottom of the screen. Drag up until the view is at the extreme 'south' pole, looking directly upward, so that you see the bases of the pyramids. Then, without releasing the mouse, drag diagonally in the up-left or up-right directions. I expect the view to rotate in azimuth about the center of the screen, but no motion occurs. I think that if I could drag the mouse on a perfectly horizontal direction at this point, instead of on a diagonal, there would still be no motion.

The strategy of this patch is to keep the view slightly away from the pole. I didn't want to touch the tolerance `EPS` because it seems like the calling code should be able to restore the sticking behavior by setting `minPolarAngle` and `maxPolarAngle`.

Would a screen capture movie help here to illustrate?