... Nick, Your clue of emacs version prompted meto upgrade my emacs. after which I'm able to do it.BTW,  my earlier emacs version was 21.2.4 and now it is 22.0.50.1One more question: I'm still not able to open the file another emacswindow. I thought this was supposed happen automatically. In otherinstances of emacs ( like when debugging apps ) the source code fileopens automatically in another ...