I would like to be able to set the transparency and fill of components in my app as I did in FB3.
Since the docs say that you can mix Halo and Sparc components, I tried simply changing my component over (by flipping the "s" to an "mx" in the MXML file) and when I do that I then get the familiar properties in the dialog. However they don't work. I can set the transparency, but fills and gradients simply don't function. The value gets set in the MXML, but they don't do anything when the app runs.
I'm running these in Air so the top level component is a WindowedApplication. I have tried changing that container as well, but it didn't seem to help.
Should I be able to do what I'm trying to do?
As far as I'm aware the "Flex 4 Halo" components (e.g. mx:Button which uses Spark skinning and is visually different to the old mx:Button in Flex 3) do not and possibly will not support all of the styles the Flex 3 Halo components supported, nor do they support the styles available to the Spark components.
So the two are not interchangeable. You mentioned switching s: to mx: which is the reverse of the usual direction, but if you want to have the styling options available to your Halo components that were previously available in Flex 3, you can add the compiler flag -compatibility-version=3 (also -theme=halo.swc but I believe that's done automatically now).
Hopefully someone can correct me if any of this is inaccurate but this is how understand it right now.