Mike, your reply solved my problem. I am working with a series of files in a folder called "Experiments," and each time I opened the Resources Palette I selected and navigated into that folder, producing an alphabetical list of its files; it was from this list that I couldn't open the symbols for an open file. But if I leave the dropdown file list as it first appears, my open files appear (as you said) at the bottom of the, and I can look at their symbols normally, and edit them. Many thanks!(I should mention that now I do find this clue in a diagram in Janis's book, p. 98, where obviously I hadn't paid sufficient attention.)