Created by: GerHobbelt
This is a redo of #1878 -- trouble there was I had prepped the patch against develop branch but had picked the master branch in the GitHub 'Open New PullReq' UI.
fix: HUB.Startup.signal.Post() API expects a single message STRING, so we must concatenate parts into a single string before queueing a call to this API. Fixes crash in HUB.Startup.signal.Post() itself where code expects a string type call parameter, rather than an array type parameter.