Up to now, ScreenExtemsions.TryActivate(newItem) was called
before Conductor.ActiveItem was set to the new item. This commit moves
setting ActiveItem to before TryActivate(newItem) call. This allows for
nested activation - that is, a scenario where newItem can "intercept"
its activation and force parent Conductor to immediately activate
another item inside its OnActivate() override, effectively skipping
newItem without displaying it.
Fixes#140
There's no nice way to make it work alongside CanCloseAsync when you're
in a conductor hierarchy. There will always be difference between how
CanClose and CanCloseAsync behave when there are children which need
to be interrogated as well, and that's confusing.
This takes the old flag-based state management in Screen, and replaces it
with one based on a ScreenState enum. This also gives a way for
interested parties to query the current state, and for an event which
notifies of any state transition.
This meant combining IActivate, IDeactivate, and IClose. This is a sensible
move: these interfaces were inextricably linked anyway, and separating
them had no advantages and a few disadvantages. If external parties are
using these interfaces directly, then migration is necessary, but these
are usually only used by Conductors
T.M
Antony Male