I was going to enter a new issue into Adobe JIRA Flex SDK bugbase that I could confirm to be present in the most recent milestone Adobe Flex SDK release 126.96.36.19910, shipped together with an August 2008 Flex Builder 3.0.1 update.
Just before submitting the bug issue, I’ve tested the functionality under the question under the latest Adobe Flex SDK stable build (188.8.131.5294 at the time of writing) – and I was surprised to find out that the bug is already fixed. Joy! Joy!
I rushed to find the reasoning for this change for UITextFormat class by reading change notes at Flex SDK download section at Adobe open source web-site, but could not find any remarks regarding this change – would be handy to have a better insight behind this change for the community.
ps If you wonder, the issue was incorrect implementation of an internal function copyFrom from UITextFormat class. UITextField’s public getUITextFormat() method relies on this copyFrom function to return UITextFormat object for the UITextField class instance. In a nutshell UITextFormat object is just a wrapper around textFormat class that should contain all the properties from wrapped textFormat class instance + add some additional functionality.
As it turned out, In Adobe Flex SDK 3.1 and below, 7(!) different properties were not copied into UITextFormat object from existing textFormat format object because of wrong implementation of UITextFormat.copyFrom function.
Now, we are safe, this particular issue is fixed!