On a Mac (my Mac at least), when you want to copy a block with its associated NBT data you have to use 'command+pickblock' instead of 'control+pickblock'. Bug MC-69399 posits the view that this should be the correct behavior, but I wonder if it is.

It's true that on Macs (of any OS version) the command key is the functional equivalent to the control key in Windows, so on the one hand going with 'command+pickblock' on OSX is consistent with how the rest of the system behaves to an extent. On the other hand, there's the argument that any non-configurable keys should be the same internally across all versions of Minecraft regardless of the host OS to prevent confusion.

I think at some point, someone should sit down and figure out what's the right way to go here. Either make these keys configurable, make them consistent across all versions of Minecraft (and actually work), or make them consistent with the host OS's conventions and clearly indicate this in all the documentation/FAQs/wikis. I don't have an opinion personally other than to say that whatever the decision ends up being, it should be a decision and not basically random like it is now.

Also: I expect this bug to be rolled into the MC-68797 superbug for all Mac bucky key issues, but I figured I'd write it out anyway just so it's documented somewhere.