Disable user-select for menu bar

Needing to cut and paste the text from a menubar isn't terribly useful
and makes the user experience unpleasant. Disable it.

Signed-off-by: Yan-Fa Li <yanfali@gmail.com>
Refactor for increased clarity

- add some docco

Signed-off-by: Yan-Fa Li <yanfali@gmail.com>