cannot use maxDisplayedLines attribute when a :over pseudo selector is declared

Steps to reproduce:
1. Create a button skin; set maxDisplayedLines=2 on the label component.
2. Add an unused css selector: .notUsed:over at root level.
3. Declare instance of button that uses skin; set label to something that will wrap.

Actual Results:
When rolling over the button, the text will flicker to a single line, then re-render as 2 lines.

Expected Results:
Expect text to remain unchanged.

Workaround (if any):
Don't use pseudo selector? When pseudo selector is deleted, it works fine.

Note that I included Peter deHann's skins also as test cases. (http://blog.flexexamples.com/2010/04/10/creating-a-multiline-spark-radiobutton-control-in-flex-4/)

I confirmed the issue on OS X 10.7 (Chrome) and Win7 (IE9). I also compiled it against SDK 4.1, 4.5, and 4.5.1, where it was easy to reproduce each time.

The effects are identical to SDK-28639 (https://bugs.adobe.com/jira/browse/SDK-28639)