This results in another problem for us:
The button to open the window with the diagram also has a tooltip and the tooltip does not close once the window is opened.
I updated your example to reflect this scenario: http://dojo.telerik.com/IGUke/10
Also we feel uneasy using this workaround as the css class is used by many other components like drop down menus and we are afraid that this may have adverse side effects that might not be discovered by our testers.
We are currently also considering to create the tooltips manually by listening on the mouseenter and mouseleave events.
Can you give me any information if and when this might be fixed?
This would help us in determining how we solve this problem in the long run.