These are chosen by the menu adjacent to the menu bar. Normal mode Left button. If the left mouse button is clicked and released with motion, the molecule is rotated.
Horizontal motion rotates the molecule about axis three.
If the left mouse button is clicked and released without motion, the starting fields are set to the appropriate specifiers for that area. If the middle button is clicked and moved, the molecule is rotated about axis 2. If the middle button is clicked and released without movement, the molecule ending fields are set to the appropriate specifiers for that area about axis 2. The right button is used to select atom pairs for distance monitoring. Clicking sets the identity of the first atom, while releasing picks the second.