Atom clicked with mouse:
Is ignored (startup default).
Becomes center of rotation.
Is identified.
Toggle atom label on/off.

Multiple atoms clicked:
Distance, Angstroms (2 atoms).
Angle (3 atoms).
Dihedral angle (torsion, 4 atoms).

HIDE:
Hide water.
Show water.
Hide DNA.
Hide protein.

White background.
Black background.