Okay, I've had a MacBook (first Apple computer) for a few months now and still I'm unable to figure out how to know when, if I hold down the mouse over a file in Finder and drag around, it will drag/drop the file or select more files, except that it seems whichever one I want to do is the one it doesn't do. It gets especially annoying to try dragging a group of files, only to find that Finder decided to get rid of my selection and start highlighting new files instead. So, what's the deal? How do I do each of these things? What's the way it tells what to do? Thanks!