Add flag country in bar of selection language

How do I put the picture of a country's flag in bar of selection language?
I saw at some installations Inno and do not know whether this feature can be added to NSIS
I want to look like this image

This has been discussed many, many times on all possible web portals for all possible software 🙂

See this article: Why you should not use a flag as a symbol of language http://www.cs.tut.fi/~jkorpela/flags.html