Known bug on Mac, discussed numerous times already. Do a search, please.
Thanks for your help.
Well, while mods didn't lock this thread yet
1. Turn on "Application Frame" under menu "Window".
and / or
2. Navigate to Preference -> Advance Type -> Type Contextual controls and uncheck it.
Thanks very much for that, on first impressions it appears to have worked. I did use the search facility originally, but it threw up a load of unrelated threads. Will try to be more specific next time.
Thanks again for your help.