The "deactivate" signal
is emitted when either a GtkMenuItem within
the current menu has been selected or the menu has been cancelled.
This signal initiates the menu's deactivate routine, which removes
the key and pointer grabs from the menu and deselects any selected
item before popping the menu down. It is largely used internally,
and probably carries more overhead when called than the
"selection-done" signal
emitted under similar conditions.
