Themes Under Gnome

[Stephen Morris]

Hi,

I can't see anywhere within Gnome Settings or Gnome Tweak Tool an 
option that allows me to set the global system theme nor the global 
colour scheme, plus the ability to view what each of these will look 
like and to be able to fine tune them if necessary. Is this 
functionality just not available under Gnome like it is under KDE?

regards,

Steve