I'm embarrassed to say it, but for the last 5 years that I've been using a mac, I've never known how to do a relatively simple task on my PC. Say I have a folder with 15 images in list view. I press "cmd a" to select all the items in the folder. Now, let's say I want to de-select files 5 through 10. How do I do that? On a PC, I would just hold ctrl, then hit file 5, then hold ctrl+shift, and hit file 10. But, on the mac, when I do that (with cmd rather than ctrl), it simply deselects 5 and 10. I would think, intuitively, this should work. If I'm selecting (rather than de-selecting), then cmd+shift works just fine!