Thanks for your reply DonCaron and SamSpayed. Appreciate it.
Unfortunately the full screen method and the changing resolution in 'system preferences - display, doesn't work.
This is a real conundrum. The wgt game window doesn't have the standard methods of reducing the window size - ie A green tab located next to the exit and minimise tabs. No arrows for reducing the size of the window by dragging the corner or edges of the window.
I think I've tried every method for reducing the size of the window, but nothing. Suppose I will have to email wgt for any further advice. Probably going to look stupid when a simple solution comes up, lol but at this time I need a 'eureka!! I have found it' moment.