You have landed on the correct approach to creating a chromeless app skin.
Can you please file a bug against Flash Builder and provide your example?
Hi setting property's in mxml makes them execute directly in the design view so it's normal you don't see annything. To "bypass" this just wait to set the alpha of the window to zero until the creationCompleteEvent is fired and set the alpha value in the event-handler.
Well that's what I do
Has this been remedied in Beta 2? I'm not having any luck doing it the way I have with Flex 3 for sometime:
<!-- The type of system chrome to use (either "standard" or "none"). Optional. Default standard. -->
<!-- Whether the window is transparent. Only applicable when systemChrome is none. Optional. Default false. -->