Description of problem:
Delete All button is showing enabled, even there is no message

Version-Release number of selected component (if applicable):
RHQ
Version: 4.1.0-SNAPSHOT
Build Number: a98c893

How reproducible:
Every time


Steps to Reproduce:
1.Login into RHQ
2.Go to the message centre by clicking on button "Message Centre" and remove  
  all the messages 
3. Navigate to Administration tab.
4. Create a user.
5. Go to the message centre by clicking on button "Message Centre" 
6. Select message and delete the message by clicking on Delete button.
  
Actual results:
Still Delete All button is showing enabled. If user clicks on the "Delete All"
button, still it prompts with yes and no options.

Expected results:
If there is no messages, Delete All button should be disabled.


Additional info:
Whenever user goes to the "Message Centre",if there is no message, the "Delete All" button should be disabled.