2MasterShin: you DON'T need a special module. Just uncheck 'Show the Language bar on the desktop' at
Control Panel -> Regional and Language Options -> Languages -> Details -> Language Bar.

It isn't a solution, but a way to avoid the problem :)
I'm just interested, why switching doesn't work with the enabled option, named before.

Sadly that test module doesn't solve the problem too :( But as (now) I know from docs, it was wrong suggestion from the beginning :)
ITfLangBarMgr isn't an interface, which can help with THIS problem, it has another functionality...
OK, let's continue with docs reading %)