Alt-Drag of Containers to Copy

Well, why would this Alt-Drag:

lead to this result:

The 'D.01' box did go where I wanted and expected it to, but the deletion of it from the original location makes no sense to me.

You must keep Alt pressed until the object is dropped

Sorry to say, that doesn't work here.   

I'm on Windows (not Mac), if that matters.

Windows may use a different modifier key for copy. You should see a plus sign appear next to the icon.

Aha!   

For Windows the Ctrl- key causes the copy, and the plus sign does appear, and a copy gets made (and labeled as such).

Thanks!

The web manual can show hotkeys only for one platform. 

What does this really mean?   

Are the manuals somehow auto- generated from platform code, meaning that you can't cite hotkeys for two different platforms because the generator has no cross-platform knowledge?

In this case, you'd need to generate two manuals for two platforms.

There are two basic scenarios:

a)  one manual, with multiple citations for the hotkeys of different platforms

b) multiple manuals, each citing only the correct keys for that platform

If you can't do one, you sorta must do the other (or face serious negative implications).

Online referencing is the modern/current standard/expectation. 

 Just punting on having the correct and complete information online is a terrible idea (IMO), as both normal and AI searches will then fall short, or actually mislead users about what they need to know.