I found problem with Ribbon menu in silverlight. I have simple ribbon menu with 2 items.
- click on main button
- menu is opening
- select or if you can don't select menu item and click anywhere besides ribbon menu
- again click on main button
- menu is not show or only blink (show and hide)
This problem is same in your demo version application such as RichEditDemo.
I used Silverlight version: 4.0.60831.0