strlen returns "the number of characters that precede the terminating NUL".
We do need to send the \0 byte, since xkbcommon on the receiving end
*is* expecting a C string. And e.g. wlroots does strlen+1.
The keys are pressed and released, not the symbols. This fixes tracking
of the state of a key through modifier changes. E.g. A capital 'A' may
be received from the client while the shift key is pressed, but if the
shift key is released before the 'a' key, the 'a' symbol is generated.
Greg V
Andri Yngvason