An action for tagging events-"Tag Event" can tag a event group with an ID(Typed by the user) and can pass it to an variable.
A condition for checking weather a sequence of events have occurred- "Has event sequence happened" along with actions to deactivate event groups with a specific ID which is defined by the user-"Deactivate event group(with ID)" which can be inverted to activate events with an ID.
An action to toggle the state of an event group from activated to deactivated and from deactivated to activated"Toggle Event group state(by ID)"
An Advantage of these actions and a condition when used with the "On nth tag executed" event(Which will require tags to be attached to events) will be be the ability to conditionally activate and deactivate events groups from the start or until some events have run which will give the users Construct 3 more control on which events to run and stop and after which sequences of actions to do that.
How is your response to the actions and conditions mentioned above,Will they make it easier for you to work with Construct 3 and if the demand for these actions and a condition is very high then I will be able to request 
Ashley to add them to Construct 3 and Please suggest improvements for these actions and a condition which I have written to make them more useful,Cheers.