Why do the faint stars and non-Messier deep sky objects disappear when I am scrolling the display?
When you update the display’s central position, KStars must recompute the pixel coordinates of every object in its database, which involves some pretty heavy trigonometry. When scrolling the display (either with the arrow keys or by dragging with the mouse), the display becomes slow and jerky, because the computer is having trouble keeping up. By excluding many of the objects, the computer can keep up and the scrolling becomes fast and smooth!
