Language box
Some keys and values under
HKEY_CURRENT_USER\Keyboard Layout define which languages and keyboard layouts can be chosen in the language box.
The following language box shows three languages and two keyboard layouts: 
The available languages are determined as values under
HKEY_CURRENT_USER\Keyboard Layout\Preload.
In the following configuration, there are three values shown in hexadecimal: 409, 807 and 809: 
As per language id mappings, these values represent:
- 409: English (United States)
- 807: German (Switzerland)
- 809: English (United Kingdom).
The respective keyboard layout for those languages is assigned in 
HKEY_CURRENT_USER\Keyboard Layout\Substitutes. Here, it contains the following two mappings: 807 -> 409 and 809 -> 407. As per the same table, this maps the language German (Switzerland) (807) to the keyboard layout English (US) (409) and English (UK) (809) to the layout German (Germany) (407).