https://learn.microsoft.com/en-us/windows/win32/api/msctf/nn-msctf-itfthreadmgr?redirectedfrom=MSDN
ITfThreadMgr (msctf.h) - Win32 apps | Microsoft Learn
The ITfThreadMgr defines the primary object implemented by the TSF manager. ITfThreadMgr is used by applications and text services to activate and deactivate...
happsmicrosoftlearn