On Apr 30, 2012, at 9:54 AM, Elaine Meng wrote:

I'll try to clarify:
Picking from the screen is one way to make a selection.  Selection can also be done with menu or command.
<http://www.cgl.ucsf.edu/chimera/docs/UsersGuide/selection.html>

So, you could either select two atoms (using picking or menu or command) and then click the Create button, as in method 1 above, or use method 2 picking with doubleclicking the second atom as you pick it instead of using the Create button

Patricia,
I think the thing you're missing is that control-click will select an atom but in order to select a second atom without de-selecting the first you need to shift-control-click the second atom.

--Eric

                        Eric Pettersen

                        UCSF Computer Graphics Lab

                        http://www.cgl.ucsf.edu