Ok, I found out how to do that and thought it might be a good idea to share it. Here's what I did:
First I've enabled the debugging of the online help within Visual Studio. Following the instructions at
I've added the required registry key (short transcription just in case the link is dead in the future):
Navigate to HKEY_CURRENT_USER\Software\Microsoft\VisualStudio\11.0\Dynamic Help
and add the value
"Display Debug Output in Retail" = "YES"
The open Visual Studio (in my case 2012) and select Help->Debug Help Context
. This will open a side pane in which you can see the current keywords.
Et voilá: for workflow designers the keyword the system is looking for is the activityname itself + ".UI". Usingthat as an F-Index keyword provides the needed entries in the help file.
So everything is working now as expected. Maybe this is something you should add to the help pages of Sandcastle itself?
Best regards and happy coding!