To ensure a consistent style I decided to use a simple validator to check if a CheckBox is checked.
If the errorSkin is applied to a spark CheckBox something strange happens (look at the image below). Even if there is no text the error border looks very strange. If I use the same procedure on a mx CheckBox it works as expected.
If you want to try it for yourself try using this snippet http://captaincode.wordpress.com/2009/10/29/validating-a-checkbox-in-flex-via-mxml/ and change the mx:CheckBox to a spark CheckBox.
Is there a fix for this problem?