VE-1702: Floating toolbar for Venus

Added an event mid-transition for the Toolbar to perform its measurements.
This event is not generic, I can't imagine it would be ever used for something else, it does make debugging this already complicated piece of code even harder. To sum it up: I don't think it is a proper solution. I'm suggesting identifying dependencies (like for instance sanity check depends on toolbar being completely initialized) and then creating (perhaps) small methods, functions which let you execute and initialize particular components in desired order. (I would look at the code from before the new animation got added and see how it should be modified.)