I just found out that if I'm copying or moving files to a USB drive in OS X, and then I switch to another program, and then I switch back to Finder, the "Copy" progress indicator isn't shown anymore (it's behind Finder). This is unlike in Windows where it always keeps the copy progress indicator at the front of Explorer. I'm curious what would happen if I ejected the USB drive while it was still copying files? Would it show an error message? Hopefully I haven't ejected a USB drive in the past while a copy/move was still going on with the progress indicator behind Finder.