command/opt-D appears to be the default short-cut for drag a copy. When I use it, it only hides the dock. Am I missing something or do I just need to change the short-cut? Sorry, I'm a new Mac user. So far, it's been a fairly smooth transition.
AC19(9001), 27" iMac i7, 12 gb ram, ATI Radeon HD 4850 512mb, OS 10.12.6
I changed the short cut to control-D. I find the dock a very useful tool, so I don't want to turn it off. I also bought a mouse with lots of buttons ( Logitech makes a couple of good ones. My MX Revolution has a total of 11 buttons.) and set them up to perform the most common commands that I use. Good luck.