Action.getStateType

Queries the type of the state of action.

If the action is stateful (e.g. created with [gio.simple_action.SimpleAction.newStateful]) then this function returns the #GVariantType of the state. This is the type of the initial value given as the state. All calls to [gio.action.Action.changeState] must give a #GVariant of this type and [gio.action.Action.getState] will return a #GVariant of the same type.

If the action is not stateful (e.g. created with [gio.simple_action.SimpleAction.new_]) then this function will return null. In that case, [gio.action.Action.getState] will return null and you must not call [gio.action.Action.changeState].