Bug 846127 Notification Touch effect of Clear all button does not work h...

1. Title : [Notification] Touch effect of 'Clear all' button does not work half times.
2. Precondition : None
3. Tester's Action : Bring down the notification and touch 'Clear all' button.
4. Detailed Symptom (ENG.) : Half the times, the 'Clear all' button text darkens on touch and half the times it doesn't
6. Expected : The 'Clear all' button text should darken every touch.
7. Reproducibility: Y
1)Frequency Rate : 50%
8. Gaia revision : 6916e18d1f72936e892543cf4a104a7d457f78ad

When the problem does not occur easily, touch an empty area of the notification list many times. and repeat.