My first session was the "Looking Ahead to the Next Version of Flex" session. They covered the new features including:
The new component set (Spark) is compatible with the existing component set (Halo).
Flex 4 provides for a separation of code and markup.
FxComponent (Spark) inherits from UIComponent (Halo) and is the base for all other new Spark classes.
Spark components should concern themselves with data and behavior only, and not concern themselves with appearance.
Skin is used to manage appearance.
There is a Designer/Developer Contract between skin and components based on data, parts, and states.
Flex 4 adds new graphical components that are “1st class citizens” of MXML, based on a new GraphicElement class.
FXG – new file format used by all of the design tools that understand actionscript. You can simply add a reference to these files
New text engine – supports animation, left-to-right, and dynamic rendering
Revamped state mechanism – state syntax can now be included inline for each control.
FxAnimate extends Effect (new class) – it is target neutral and supports auto reverse
The new state syntax is not backwards compatible. New MXML syntax (MXML 2009), previous version is MXML 2006. You can have files in different formats in the same project, but you cannot mix the syntax within the same file.
Group – new class that supersedes Component (Container?)
DataGroup – repeater done right
LayoutBase – three helper classes: vertical, hortizonal and base (canvas)
Layout now respects transistions
Layering is now divorced from child ordering
Two way data binding
Enhanced CSS support
Improved compiler performance
2X improvement for debug incremental compile
Up to 5X improvement
Data centric development