Disables client's screen-reader on keyboard's grab. This help's the user to use custom at-spi2 key bindings related to a11y in the Guest without being taken by the client's screen-reader.
Note that the toggle only enables screen-reader if it was enabled before.
Signed-off-by: Victor Toso firstname.lastname@example.org
-- Edit, this still is working in progress. Trying to find a better solution focused on keyboard itself instead of disabling client's screen-saver