Language List Autostart

Is it possible in some config file (I guess in post-session) to add something like

"Show Language List = true" (or false - what can be default settings)

As GDM don't allow users to choose language if they are logged without password (it mean public PC usage), what can be logically consequence of the fact how language must to be chosen after user selection, some command what will enable autostart (automatic) appearance of the Language List before entrance in xsession and after user selection, will be ideal solution for multilingual PC usage.

I think how question/idea/suggestion is reasonable, technically possible and over all extra functional (it will solve lot of the problems in multilingual area/countries), simple and pragmatic.

Other two choosers are undoubtedly not problematic. Keyboard can be switched in the xsession and xsession is in any case for public PC usage matter of administrator choice and security issue.

Obviously, only problem is language (big problem).