Now that I've switched to the Mac I can no longer read the Cortex help file on my main computer's big screen whilst remotely controlling Cortex via RDC.
It's one of those weird things that I simply thought I would be out of luck. Until it finally occurred to me to search Google. And I found CHMox, which is free, and it works. Brilliant.
So now I can refer to the help file and still run Cortex full screen in the RDC window.