First of all, my renewed thanks for your unstinted help, patience, detailed and prompt replies.
Have tried out your method, but did not manage to solve my problem, as the paint bucket tool would not paint the background color. It kept painting the foreground color.
I checked and re-checked the tip you sent me, but to no avail.
Why is the background color never painted?
I feel lost...
My thanks as ever, and wishing you goodnight.

Joe