Mouse/keyboard operations may be broadly separated into two categories:
selection (picking) and manipulation (translation/rotation).
The left button is used for picking of objects on screen and/or of menu items.
Left and right buttons together are used to define a selection box for copying/cutting
to the clipboard, as well as for model and color control for designated parts
of a molecule. Together with the Shift key, the left button allows
for picking over a range. Together with the Ctrl (Control) key,
the left button allows for multiple picking. Both range and multiple picking
applies not only to text items in lists, but to atoms and bonds in molecules
as well. Together with the Alt key, the left button allows for selection
of an entire group (detached molecular fragment).
The left button is used for rotation and the right button is used for translation
and scaling of objects on screen. With no modifier keys, the left mouse button
gives rise to rotation about the X and Y (screen) axes; the right mouse button
gives rise to translation in the X and Y (screen) directions. Together with
the Shift key, the left mouse button gives rise to rotation about the
Z direction and the right mouse button gives rise to scaling.
The Ctrl key in conjunction with the left or right mouse buttons and
(optionally) the Shift key, signifies a change in focus away from the
default for the purpose of rotations and translations. Outside of "build
mode", the default is focus on a single molecule (the "selected"
molecule). Use of the Ctrl key changes focus to the entire set of molecules
on screen, meaning that rotations and translations are carried out globally.
In "build mode", the default is focus on the full set of fragments
which make up the molecule being constructed, and rotations and translations
refer to this set of fragments as a whole. Use of the Ctrl key changes
focus to a single fragment (the "selected" fragment), and rotations
and translations now refer only to this fragment.
Use of the Alt key in addition to the left mouse button allows for
rotation about a "selected" bond and, in addition to the right mouse
button, for stretching of the "selected" bond.