Hi Steve, Not a dumb question - it just takes a while to learn various details. Models can be activated/deactivated for motion in several ways. As long as you have the two things opened as two different model numbers, you can deactivate one of them so that only the other is responsive to interactive movement with the mouse and movement commands (move, turn, etc.). How to activate/deactivate a model for motion: on the Midas Emulator, check/uncheck the box next to the model number http://www.cgl.ucsf.edu/chimera/docs/UsersGuide/chimerawindow.html#emulator OR choose the model in the Model Panel and use the buttons "activate" and "deactivate" http://www.cgl.ucsf.edu/chimera/docs/UsersGuide/modelpanel.html#activate OR toggle the active checkbox in the Molecule Model attributes panel http://www.cgl.ucsf.edu/chimera/docs/UsersGuide/moleculeattrib.html Your mail has alerted me that I should probably also mention this issue in the "mouse manipulation" page. Hope this helps, Elaine =-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-= Elaine C. Meng, Ph.D. Babbitt Lab and Computer Graphics Lab meng@cgl.ucsf.edu http://www.cgl.ucsf.edu/home/meng/index.html =-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=