Both SDL_TEXTEDITINGEVENT_TEXT_SIZE and SDL_TEXTINPUTEVENT_TEXT_SIZE are only 32 in size, which would fail when typing a long message in Windows IME.

To reproduce:
Open Windows 8's default Japanese IME, type "---------murasaki". The IME works correctly handling the "murasaki" part, which should have more than a few candidates. But SDL returns clipped text in both edit and input messages, resulting in the text being clipped to 10 characters.

Typing more than 32 bytes is typical in the default Microsoft IMEs which can handle very long sentences. To be completely safe, the buffer should be increased to at least 256 bytes (which is the limit of the Win 8 Microsoft Japanese IME), or at least the interface should be designed to send multiple messages (e.g. with clobbered editing, at least send enough SDL_TextInputEvents to cover all the text).