Yes, drag and drop works between different servers. For two windows from the same server I want to copy (using opt-drag), not move. Hence the move command isn't appropriate. I've just tried again with different folders and the opt-drag "worked" in that there was no error -- however, the file was moved, which was not what was wanted. I've had this happen a few times in the past without my realizing what was going on, and with consequential scripting problems caused by the source file disappearing!
If you could implement the opt-drag that would be great! Thanks.