Reduce the number of allowed Event types

We have states and transitions available, so switching layouts is not strictly needed as everything can be states.

To simplify our system's operating concept, we could remove the layout switching possibility and use only states. While at it, we ought to remove all other ways to dynamically change colour, opacity, position etc. except for dynamic text, whose content is not known during design time. For everything else, we should allow property changes from explicit states only, which could be validated during design time. I.e. remove support for most of the events expect for state change.