Daniel,

> First a general one - it seems from reading this that there exists a
> mouse event focus. Isn't focus only relevant to keyboard events?

No.

> as a
> user of windowing systems, I usually assume the mouse even will be
> handled by precisely whatever is under it...

Only upon mouse down events and only if there are no modal dialogs/windows.
In all other cases the mouse input will go somewhere else. This is true for
all systems I know about.

> > When an event is dispatched it uses (sometimes varying) 
> > strategies to figure
> > out where it ends up.
> It's not very clear here who might participate in distributing the
> event. Pointers?

Like I was saying, see #dispatchEvent:. It delegates the task to
MorphicEventDispatcher.

> I'm not quite clear what you mean here - what's a front-most chain?
> start from front most, then go up the owner chain?

At each morph in the hierarchy there is one (or none) morph which is
front-most under the mouse (or more accurately: at the point where the event
occured) forming a "chain" of front-most morphs.

> When you say "the hierarchy is traversed down" you mean the case where
> there's no focus, right?

Yes, that's what I said initially.

Cheers,
  - Andreas