Indicates that the action was just activated.
parameter will always be of the expected type. In the event that an incorrect type was given, no signal will be emitted.
Since GLib 2.40, if no handler is connected to this signal then the default behaviour for boolean-stated actions with a null parameter type is to toggle them via the change_state signal. For stateful actions where the state type is equal to the parameter type, the default is to forward them directly to change_state. This should allow almost all users of SimpleAction to connect only one handler or the other.
| parameter |
the parameter to the activation |