Append a keystring to the input buffer
int SLang_buffer_keystring (unsigned char *b, unsigned int len)
SLang_buffer_keystring places the len characters
specified by b at the end of the buffer that
SLang_getkey uses. Upon success it returns 0; otherwise, no
characters are buffered and it returns -1.
The difference between SLang_buffer_keystring and
SLang_ungetkey_string is that the SLang_buffer_keystring
appends the characters to the end of the getkey buffer, whereas
SLang_ungetkey_string inserts the characters at the beginning
of the input buffer.
SLang_getkey, SLang_ungetkey, SLang_ungetkey_string