[SparkSkins] emphasized MX Button doesnt show error string border

Found in 4.0.0.13286

Steps to reproduce:
1. Compile and run attached MXML file.
2. Check/select the errorString CheckBox control.
3. Note that there is no red border around the mx:Button+emphasized button (but works on other 5 buttons).
4. Roll over each of the 6 buttons and note each one does show the error string correctly.
5. Tab through each of the 6 buttons and note the red highlight border DOES appear correctly.

Actual Results:
The emphasized mx:Button doesnt have a red border to show that there was an error or it failed some validation.

Expected Results:
The emphasized mx:Button should have a red border like the other states. Otherwise it makes it near impossible to visually tell if the Button has an errorString without rolling over it or tabbing to it.

Workaround (if any):
n/a