Here I trace a mouse event that is sent into the 3d space. This is based
on the 3.8 Cobalt. The way this works on 4.1 Cobalt is a little simpler.

---- Morphic Event Loop (event processing phase) ----
- as part of the event loop (WorldState >> doOneCycleNowFor:)
- Morphic processes events (HandMorph >> processEvents)
  - It reads the event from the VM (EventSensor >> nextEvent)
  - The event dispatcher decides the event is inside CobaltBrowser and
    asks it to handle the event (CroquetParticipantWithMenu >>
    handleEvent:)
  - Cobalt forsakes normal event handling and simply dumps the raw event
    into the Tweak event queue (CroquetParticipantWithMenu >>
    handleEvent:)

---- Morphic Event Loop (stepping phase) ----
- CroquetParticipantWithMenu >> step
  - CroquetParticipantWithMenu >> runTweakCycle
    - CroquetMenuWorld >> runCroquetCycle
      - Start the Tweak script CHandPlayer >> processEventsFrom: to read
        the events from the world queue
      - Run the scheduler to run the script processes

---- Tweak Script: CHandPlayer >> processEventsFrom: ----
- Start the script CHandPlayer >> dispatchEvent: with the event

---- Tweak Script: CHandPlayer >> dispatchEvent: ----
- the hand signals #mouseDown; nobody is listening (self signal: evt
  type with: evt)
- the hand sets lastEvent
- the hand signals #updateMouseOver, which will trigger CHandPlayer >>
  onUpdateMouseOver later to see if the cursor needs changing
- The hand dispatches the event (CHandPlayer >> sendMouseEvent)
- The dispatcher decides the world should handle it (CPrimitiveCostume
  >> handleMouseDown:)
- stuff