Upgrading Flex from 3.2 to 4.5 - Errors and Warnings - apache-flex

Question

I've inherited a large codebase written primarily in Flex 3.2 using Parsley and Cairngorm.
The entire build process is done through maven using FlexMojos.
I'm relatively new to Flex and I've been told to upgrade Flex from 3.2 to the latest 4.5.1 version.
While I have made a good progress, I have run into some errors that are beyond my understanding or Google search has not been able to help.
Things I have done:
Changed all namespaces to mxml 2009 and fx.
Put all non-visual components in fx:declarations.
Added namespaces in my stylesheet
Upgraded version of FlexMojos to 3.9 - not 4 because there isn't a stable version yet
Upgrade all cairngorm dependencies to the Flex 4 dependencies, although keeping the same versions.
Exclusively declared that the theme I want to use in the compiler settings is halo.swc
Fixed a lot of compilation warnings and errors which were trivial.
Things I don't know how to fix:
While compiling, I get a lot of warnings with regards to CSS.
An example of warning I get is the following:
[WARNING] C:\repo\com\adobe\flex\framework\framework\4.0.0.14159\framework-4.0.0.14159.swc$defaults.css:[487,-1]
The style 'dropShadowVisible' is only supported by type
'mx.controls.List' with the theme(s) 'spark'.
For a start, I'm not using 4.0.014159, although something's telling me that the dependency is being pulled through a Cairngorm library such as validation or module.
If so, any solutions to that?
Additional warnings I get which I don't understand how to fix are the following:
[WARNING] The swc
'C:\repo\com\adobe\flex\framework\framework\4.5.1.21328\framework-4.5.1.21328.swc'
has style defaults and is in the library-path, which means
dependencies will be linked in without the styles. This can cause
applications, which use the output swc, to have missing skins. The
swc should be put in the external-library-path.
Regarding the above, I read somewhere that the swc file has to be loaded as an external library path instead. I did that but the warning didn't go away.
Finally, the app fails to compile as a result of these errors.
[ERROR]
C:\repo\com\adobe\flex\framework\mx\4.5.1.21328\mx-4.5.1.21328.swc$defaults.css:[469,-1]
Invalid Embed directive in stylesheet - can't resolve source
'Embed(source = "assets/CalendarIcon.png")'.
There's no reference of the CalendarIcon.png asset in my codebase. Google pointed me out to this http://python.mmitd.com/bugs.adobe.com/jira/browse/SDK-22746, but I'm afraid nothing I've done worked.
As you can see the majority of my warnings/errors (at least for now) lie around default.css warnings.
Any help will be greatly appreciated!

Answer 1

Flex compiler, by default uses a css, which is named as "defaults.css". If you have the css named as "defaults.css", change the name of it.
It will also look for flex-config, which should be same as application name or it will take a default flex-config from the sdk folder. There are couple of css properties, which are only available in Flex 3 components. Now as we have the Spark component architecture in place, few properties may not work at all and give you warning messages.
If you have Flash Builder installed on your machine, you can import your project in it and go through the warning messages one at a time and fix your .css file.
Hope it helps you somewhat in resolving the problems..