Thank you for the provided project.
We were able to reproduce the described issue with the exact version of our controls you are using.
Fortunately this issue is fixed in our latest release of "UI for Windows Phone 8".
Please note that the version used (Q1 2014) was the last version released for Windows Phone 7.
And we highly recommend upgrading your project(s) to Windows Phone 8 and using our latest releases for it since they contain a lot of fixes and improvements.
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