The next few posts will be dedicated to common errors that arise from moving to Flex 4.5 SDK and Spark Theme.

First, let me explain why those errors arise. When changing the compiler SDK to Flex 4.5 some errors arise and are easily fixed.
When you change the theme to Spark Theme, some styles are no longer supported for mx components.

If you plan a complete migration, you will replace those with Spark equivalents and all will be good.
If, however, you only plan a partial migration, then you won’t necessarily replace all components but you will have to handle those errors.

The first one will be borderThickness and backgroundAlpha styles, which are no longer available for some mx compoments under the spark theme.
Let’s review an example (code was modified to protect customer code):

I am currently doing some migration work for a client, migrating their Flex 3.5 application to Flex 4.5.

Occasionally, I will undoubtedly encounter bumpers…
This will be an account of those bumpers, and how I came to resolve them. This is not guaranteed to be the best solution, just the one that worked for me, usual caveats apply.

The application I am migrating is built of modules, and every time I ran the app I got an exception on UIComponent’s getStyle method. Nothing I did fixed this, until I found this link.

It describes a compiler flag, namely ‘isolate-styles’ which, when set to false, you can prevent merging of styles between the modules and the main application.