Hi Kjell,
I am afraid that I was not able to reproduce the issue. I tested the issue with your code snippets under below system configuration:
Microsoft Windows XP
Professional
Version 2002
Service Pack 2
OS language - English
Regional Options - English(United States)
Essential Studio version - 5.2.0.25
Here is the video clip your reference:
http://www.syncfusion.com/Support/user/uploads/TestVedio_f3905bfc.zipPlease take a look at the above video clip and let me know if I am missing something and also let me know if there are any configuration changes, so that I can test in that environment and sort out the cause of the issue and provide you a solution.
Thanks,
Melba