Turn it Off and On again !!!
You know that age old IT help desk trick of turn it off and on again ... well that work !
Yesterday, I'd closed DW, uninstalled the extension, reinstalled it, and then re-opened DW ..the Show region tab didn't open
Today, having shutdown the computer completely overnight, I have just re-tried and it now opens the Show region tab
Why ..I have no idea, I'm sure there will be technical explanation for this, but next time I have a minor bug like this I will.. Turn it Off and On again !!!
PS and thanks for the Skype time offer ..as always you do as the name suggests.. by offering WebAssist(ance) !