Is there any particular reason why the base locale isn't available as an option in the Translations/Locales menu?
For example, I want to support Arabic, but only the Arabic locale in general e.g. 'ar', which isn't available by default in the menu.
I don't want to have to choose a country e.g. United Arab Emirates etc, as this ties the country code to the locale. Sure, I could strip the country code from the locale code in my app, but then I wouldn't be able to use some country codes in other locales if I wanted too, since I'd be stripping all the country parts away. I might want to support Cantonese and Mandarin for example, and then would need zh-hk, and zh-cn, so in this instance I need the entire code.
I know I can make my own locale code, which is awesome, and this is what I've been doing.
But if you do this you lose the ability to have flags, so maybe we could have an option to choose our own flag for the custom locale? As when you are on the list view and only see flags, this becomes very useful.
Also, by using custom locales, we would lose any locale specific options that may be present in the editor. For example, in Contentful, if you choose any Arabic locale (e.g. 'ar'), then in the WYSIWYG editor the RTL rules are applied by default. This is quite good implementation of the locale/RTL logic, because then you don't need to worry about formatting the RTL content, it's automatically applied in the editor, including lists : )