Spark Button control doesnt show tooltips on disabled controls (works on MX/Halo)

Found in 4.0.0.13101.

Steps to reproduce:
1. Compile and run attached MXML file.
2. Mouse over each of the Button controls. You should see tooltips.
3. Toggle (deselect) the CheckBox control.
4. Mouse over each of the Button controls.

Actual Results:
After the enabled property gets set to false, the tooltips no longer appear for the s:Button controls (but still appear for mx:Button controls).

Expected Results:
The behavior should probably be consistent. The mx:Button behavior is the same in a Flex 3.5 app. I'm thinking that a disabled s:Button should still show it's tooltip.

Workaround (if any):
n/a