it's related to the stupid SDL, we use it for capture normal keyboard press, but which do not support unicode indeed. so to support unicode, I try to support system input method, which send out text by gui message, but which do not and can not auto-filter the original generated keyboard press sdl events, then here I had to ifdef it.
another method to workaround it is that add a method to check when IsTextInputEnabled() we ignore the keyboard events here.