While investigating how to send capital-letter to an application, I found the message WM_CHAR.
Apparently, this message is not generated by the OS, but by TranslateMessage.
TranslateMessage get the WM_KEYDOWN, and if it is a character, check the modifiers, (such as shift, caps-lock, and other keys) and emit a WM_CHAR.
TranslateMessage is an kernel-level function, and check the status of the physical keys. so you can't mess with it. Also, because it is kernel-level, the message looks like the OS sent it.
