JavaScript buttons not showing in Browser Control

I'm working on an upgrade from Adobe Reader X to Reader DC and I've run across a problem getting some JavaScript buttons to show up. In Reader X, I was able to get these buttons to show in the tool bar (in both desktop and browser mode) using the following registry values:

[HKEY_CURRENT_USER\Software\Adobe\Acrobat Reader\10.0\AVGeneral\cFavoritesCommandsBrowser]

"a0"="_legacy:printButton"

"a1"="_legacy:submitButton"

"a2"="_legacy:saveButton"

"a3"="_legacy:closeButton"

I've tried applying the same values to the corresponding Reader DC registry key and I'm getting strange results. The buttons do show up as a floating toolbar (labeled "Add-on tools") when in desktop mode, but they don't show at all when documents are loaded via the Adobe PDF Browser Control (AcroPDFImpl.dll).

Is there a way to get these tools to show when a document is loaded via Adobe PDF Browser Control? Also, is there a way to get them to show inline with the other tools? I have tried using related keys found in the Adobe Enterprise Toolkit Windows Registry Reference but with no success.