I think I have a decent workaround to this old bug, where you run into formatting problems if you want to use a custom borderSkin on a Panel or Alert. (I especially wanted to use a skin created with Degrafa.) In addition, I wanted to set up something where I could create a generic Panel skin to use throughout my application, but also use the skin for Alerts without it messing up the title bar. Even though it’s over a year old, this post is still getting remarks about the layout bug.
Admittedly, my workaround is a total hack. However, that’s why it’s called a workaround. I’ve been using it without issues, and wanted to make it public. Click here to download a Flex project archive with the solution files. This is what it looks like: