Dear Ibrahim, If I understand correctly, you want to get back the selection you had before, which is the same as the atoms that are displayed. If that selection was the most recent, "Select... Undo" would restore it. The same thing is accomplished by pressing the left arrow key after clicking into the graphics window. If that doesn't work (if you did some other selections in between), you can re-select just the displayed atoms with the command: select @/display Then you can proceed with hbond and one of its "selRestrict" options. For future reference, you can name and save a selection ("Select... Name Selection" in the menu or the command "namesel") and then later restore that selection by choosing its name from the menu under "Select... Named Selections". http://www.cgl.ucsf.edu/chimera/docs/UsersGuide/midas/namesel.html I hope this helps, Elaine ----- Elaine C. Meng, Ph.D. meng@cgl.ucsf.edu UCSF Computer Graphics Lab and Babbitt Lab Department of Pharmaceutical Chemistry University of California, San Francisco http://www.cgl.ucsf.edu/home/meng/index.html On May 8, 2008, at 2:03 PM, Ibrahim Moustafa wrote:

Dear Chimera team, How to include residues previously selected and shown on the screen with a new selection? For example, I did a selection for few residues and displayed them on the screen; then removed the selection. I wanted to run hbond on those residues already on display. How to do that?

Thanks, Ibrahim