I have located the registry key which controls which global themes are shown within 'Aero Themes'. If you right-click the desktop you only get 1 global theme based on your location (United Kingdom, South Africa, United States, Canada & Australia).
There is a very simple method with which to add all the above to the 'Aero Themes' section rather than as 'Installed Themes'. Just run regedit and navigate to
HKEY_CURRENT_USER\Software\Microsoft\Windows\CurrentVersion\Themes\InstalledThemes\MCT
an add the following string values (edit->new->string value)
1, C:\Windows\Globalization\MCT\MCT-AU\Theme\AU.Theme
2, C:\Windows\Globalization\MCT\MCT-CA\Theme\CA.Theme
3, C:\Windows\Globalization\MCT\MCT-GB\Theme\GB.Theme
4, C:\Windows\Globalization\MCT\MCT-US\Theme\US.Theme
5, C:\Windows\Globalization\MCT\MCT-ZA\Theme\ZA.Theme
(See Pic 1)
NOTE: 1 of these will already be listed in your registry, just add the 4 that aren't
Now, whenever you richt-click the desktop & Personalize, you will have the above listed themes showing as 'Aero Themes'. (See Pic 2)
Jeff